| IAA | Wisconsin | Anthem Blue-Cross Blue-Shield of Wisconsin |
| IAB | - | Unallocated/Not Assigned |
| IAC | Oregon/Idaho/Utah/Washington | Regence Blue-Cross Blue-Shield |
| IAD | Indiana | Anthem Blue-Cross Blue-Shield of Indiana |
| IAE | Michigan | Blue-Cross Blue-Shield of Michigan |
| IAF | - | Unallocated/Not Assigned |
| IAG | Virginia | Anthem Blue-Cross Blue-Shield of Virginia |
| IAH | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| IAI | - | Unallocated/Not Assigned |
| IAJ | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| IAK | California | Blue-Shield of California |
| IAL | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| IAM | California | Blue-Shield of California |
| IAN | - | Unallocated/Not Assigned |
| IAO | - | Unallocated/Not Assigned |
| IAP | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| IAQ | - | Unallocated/Not Assigned |
| IAR | Alabama | Blue-Cross Blue-Shield of Alabama |
| IAS | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| IAT BCBS Prefix | New York | Empire Blue-Cross Blue-Shield of New York |
| IAU | Nebraska | Blue-Cross Blue-Shield of Nebraska |
| IAV | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| IAW | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| IAX | - | Unallocated/Not Assigned |
| IAY | South Carolina | Blue-Cross Blue-Shield of South Carolina |
| IAZ | - | Unallocated/Not Assigned |
| IBA | Illinois | Blue-Cross Blue-Shield of Illinois |
| IBB | New Jersey | Horizon Blue-Cross Blue-Shield of New Jersey |
| IBC | Wisconsin | Anthem Blue-Cross Blue-Shield of Wisconsin |
| IBD | Wisconsin | Anthem Blue-Cross Blue-Shield of Wisconsin |
| IBE | Illinois | Blue-Cross Blue-Shield of Illinois |
| IBF | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| IBG | - | Unallocated/Not Assigned |
| IBH | Alabama | Blue-Cross Blue-Shield of Alabama |
| IBI | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| IBJ | Michigan | Blue-Cross Blue-Shield of Michigan |
| IBK | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IBL | Pennsylvania | Independence Blue-Cross of Philadelphia and Southeastern Pennsylvania |
| IBM | California | Blue-Shield of California |
| IBN | - | Unallocated/Not Assigned |
| IBO | Pennsylvania | Independence Blue-Cross of Philadelphia and Southeastern Pennsylvania |
| IBP | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| IBQ | Oregon/Idaho/Utah/Washington | Regence Blue-Cross Blue-Shield |
| IBR | Michigan | Blue-Cross Blue-Shield of Michigan |
| IBS | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IBT | Illinois | Blue-Cross Blue-Shield of Illinois |
| IBU | Alabama | Blue-Cross Blue-Shield of Alabama |
| IBV | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| IBW | Illinois | Blue-Cross Blue-Shield of Illinois |
| IBX | California | Anthem Blue-Cross |
| IBY | - | Unallocated/Not Assigned |
| IBZ | Oregon/Idaho/Utah/Washington | Regence Blue-Cross Blue-Shield |
| ICA | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| ICB | - | Unallocated/Not Assigned |
| ICC | Colorado | Anthem Blue-Cross Blue-Shield of Colorado |
| ICD | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| ICE | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| ICF | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| ICG | Louisiana | Blue-Cross Blue-Shield of Louisiana |
| ICH | Virginia | Anthem Blue-Cross Blue-Shield of Virginia |
| ICI | Florida | Florida-Blue |
| ICJ | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| ICK | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| ICL | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| ICM | California | Blue-Shield of California |
| ICN | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| ICO | North Carolina | Blue-Cross Blue-Shield of North Carolina |
| ICP | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| ICQ | - | Unallocated/Not Assigned |
| ICR | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| ICS | - | Unallocated/Not Assigned |
| ICT | New York (Western) | Blue-Cross Blue-Shield of Western New York |
| ICU | - | Unallocated/Not Assigned |
| ICV | Michigan | Blue-Cross Blue-Shield of Michigan |
| ICW | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| ICX | - | Unallocated/Not Assigned |
| ICY | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| ICZ | - | Unallocated/Not Assigned |
| IDA | Idaho | Blue-Cross of Idaho |
| IDB | Florida | Florida-Blue |
| IDC | - | Unallocated/Not Assigned |
| IDD | Virginia | Anthem Blue-Cross Blue-Shield of Virginia |
| IDE | Idaho | Blue-Cross of Idaho |
| IDF | Idaho | Blue-Cross of Idaho |
| IDG | - | Unallocated/Not Assigned |
| IDH | - | Unallocated/Not Assigned |
| IDI | California | Blue-Shield of California |
| IDJ | Virginia | Anthem Blue-Cross Blue-Shield of Virginia |
| IDK | New York | Empire Blue-Cross Blue-Shield of New York |
| IDL | Idaho | Blue-Cross of Idaho |
| IDM | Idaho | Blue-Cross of Idaho |
| IDN | Idaho | Blue-Cross of Idaho |
| IDO | Kansas | Blue-Cross Blue-Shield of Kansas |
| IDP | Idaho | Blue-Cross of Idaho |
| IDQ | Virginia | Anthem Blue-Cross Blue-Shield of Virginia |
| IDR | California | Anthem Blue-Cross |
| IDS | Kansas City | Blue-Cross Blue-Shield of Kansas City |
| IDT | Virginia | Anthem Blue-Cross Blue-Shield of Virginia |
| IDU | Louisiana | Blue-Cross Blue-Shield of Louisiana |
| IDV | - | Unallocated/Not Assigned |
| IDW | - | Unallocated/Not Assigned |
| IDX | Illinois | Blue-Cross Blue-Shield of Illinois |
| IDY | South Carolina | Blue-Cross Blue-Shield of South Carolina |
| IDZ | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| IEA | Oregon/Idaho/Utah/Washington | Regence Blue-Cross Blue-Shield |
| IEB | Indiana | Anthem Blue-Cross Blue-Shield of Indiana |
| IEC | California | Blue-Shield of California |
| IED BCBS Prefix | Indiana | Anthem Blue-Cross Blue-Shield of Indiana |
| IEE | - | Unallocated/Not Assigned |
| IEF | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| IEG | - | Unallocated/Not Assigned |
| IEH | Alaska | Premera Blue-Cross Blue-Shield of Alaska |
| IEI | Pennsylvania | Independence Blue-Cross of Philadelphia and Southeastern Pennsylvania |
| IEJ | South Carolina | Blue-Cross Blue-Shield of South Carolina |
| IEK | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| IEL | Illinois | Blue-Cross Blue-Shield of Illinois |
| IEM | - | Unallocated/Not Assigned |
| IEN | - | Unallocated/Not Assigned |
| IEO BCBS Prefix | North Carolina | Blue-Cross Blue-Shield of North Carolina |
| IEP | Louisiana | Blue-Cross Blue-Shield of Louisiana |
| IEQ | New York | Empire Blue-Cross Blue-Shield of New York |
| IER | Virginia | Anthem Blue-Cross Blue-Shield of Virginia |
| IES | Texas | Blue-Cross Blue-Shield of Texas |
| IET | Connecticut | Anthem Blue-Cross Blue-Shield of Connecticut |
| IEU | Louisiana | Blue-Cross Blue-Shield of Louisiana |
| IEV | - | Unallocated/Not Assigned |
| IEW | Illinois | Blue-Cross Blue-Shield of Illinois |
| IEX | Michigan | Blue-Cross Blue-Shield of Michigan |
| IEY | South Carolina | Blue-Cross Blue-Shield of South Carolina |
| IEZ | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| IFA | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IFB | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| IFC | New York (Western) | Blue-Cross Blue-Shield of Western New York |
| IFD | Oregon/Idaho/Utah/Washington | Regence Blue-Cross Blue-Shield |
| IFE | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IFF | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| IFG | - | Unallocated/Not Assigned |
| IFH | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| IFI | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| IFJ | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| IFK | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| IFL | Oregon/Idaho/Utah/Washington | Regence Blue-Cross Blue-Shield |
| IFM | - | Unallocated/Not Assigned |
| IFN | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| IFO | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| IFP | Nevada | Anthem Blue-Cross Blue-Shield of Nevada |
| IFQ | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| IFR | Kentucky | Anthem Blue-Cross Blue-Shield of Kentucky |
| IFS | - | Unallocated/Not Assigned |
| IFT | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| IFU | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| IFV | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| IFW | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| IFX | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| IFY | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| IFZ | South Carolina | Blue-Cross Blue-Shield of South Carolina |
| IGA | Pennsylvania | Independence Blue-Cross of Philadelphia and Southeastern Pennsylvania |
| IGB | - | Unallocated/Not Assigned |
| IGC | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| IGD | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| IGE | Alabama | Blue-Cross Blue-Shield of Alabama |
| IGF | California | Blue-Shield of California |
| IGG | California | Blue-Shield of California |
| IGH | Pennsylvania | Independence Blue-Cross of Philadelphia and Southeastern Pennsylvania |
| IGI | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| IGJ | Pennsylvania | Independence Blue-Cross of Philadelphia and Southeastern Pennsylvania |
| IGK | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| IGL | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| IGM | - | Unallocated/Not Assigned |
| IGN | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| IGO | New York (Western) | Blue-Cross Blue-Shield of Western New York |
| IGP | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| IGQ | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| IGR | - | Unallocated/Not Assigned |
| IGS | - | Unallocated/Not Assigned |
| IGT | - | Unallocated/Not Assigned |
| IGU | Louisiana | Blue-Cross Blue-Shield of Louisiana |
| IGV | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| IGW | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| IGX | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| IGY | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| IGZ | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| IHA | - | Unallocated/Not Assigned |
| IHB | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| IHC | - | Unallocated/Not Assigned |
| IHD | Nebraska | Blue-Cross Blue-Shield of Nebraska |
| IHE | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| IHF | New York | Empire Blue-Cross Blue-Shield of New York |
| IHG | - | Unallocated/Not Assigned |
| IHH | Alabama | Blue-Cross Blue-Shield of Alabama |
| IHI | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| IHJ | New York | Empire Blue-Cross Blue-Shield of New York |
| IHK | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| IHL | West Virginia | Highmark Blue-Cross Blue-Shield of West Virginia |
| IHM | Delaware | Highmark Blue-Cross Blue-Shield of Delaware |
| IHN | California | Blue-Shield of California |
| IHO | Louisiana | Blue-Cross Blue-Shield of Louisiana |
| IHP | - | Unallocated/Not Assigned |
| IHQ | Louisiana | Blue-Cross Blue-Shield of Louisiana |
| IHR | California | Blue-Shield of California |
| IHS | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| IHT | Alabama | Blue-Cross Blue-Shield of Alabama |
| IHU | - | Unallocated/Not Assigned |
| IHV | - | Unallocated/Not Assigned |
| IHW | California | Blue-Shield of California |
| IHX | Colorado | Anthem Blue-Cross Blue-Shield of Colorado |
| IHY | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IHZ | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IIA | California | Blue-Shield of California |
| IIB | - | Unallocated/Not Assigned |
| IIC | New Jersey | Horizon Blue-Cross Blue-Shield of New Jersey |
| IID | Idaho | Blue-Cross of Idaho |
| IIE | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| IIF | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IIG | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| IIH | - | Unallocated/Not Assigned |
| III | Tennessee | Blue-Cross Blue-Shield of Tennessee |
| IIJ | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| IIK | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| IIL | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| IIM | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| IIN | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| IIO | - | Unallocated/Not Assigned |
| IIP | New York (Western) | Blue-Cross Blue-Shield of Western New York |
| IIQ | Florida | Florida-Blue |
| IIR | South Carolina | Blue-Cross Blue-Shield of South Carolina |
| IIS | - | Unallocated/Not Assigned |
| IIT | Illinois | Blue-Cross Blue-Shield of Illinois |
| IIU | Pennsylvania | Independence Blue-Cross of Philadelphia and Southeastern Pennsylvania |
| IIV | Florida | Florida-Blue |
| IIW | California | Blue-Shield of California |
| IIX | Idaho | Blue-Cross of Idaho |
| IIY | South Carolina | Blue-Cross Blue-Shield of South Carolina |
| IIZ | Florida | Florida-Blue |
| IJA | Wisconsin | Anthem Blue-Cross Blue-Shield of Wisconsin |
| IJB | Kentucky | Anthem Blue-Cross Blue-Shield of Kentucky |
| IJC | - | Unallocated/Not Assigned |
| IJD | New Hampshire | Anthem Blue-Cross Blue-Shield of New Hampshire |
| IJE | New York (Western) | Blue-Cross Blue-Shield of Western New York |
| IJF | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IJG | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IJH | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IJI | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IJJ | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IJK | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IJL | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IJM | - | Unallocated/Not Assigned |
| IJN | Florida | Florida-Blue |
| IJO | - | Unallocated/Not Assigned |
| IJP | South Carolina | Blue-Cross Blue-Shield of South Carolina |
| IJQ | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IJR | Idaho | Blue-Cross of Idaho |
| IJS | Wisconsin | Anthem Blue-Cross Blue-Shield of Wisconsin |
| IJT | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IJU | Texas | Blue-Cross Blue-Shield of Texas |
| IJV | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IJW | - | Unallocated/Not Assigned |
| IJX | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IJY | Pennsylvania | Capital Blue-Cross of Pennsylvania |
| IJZ | South Carolina | Blue-Cross Blue-Shield of South Carolina |
| IKA | Kentucky | Anthem Blue-Cross Blue-Shield of Kentucky |
| IKB | Virginia | Anthem Blue-Cross Blue-Shield of Virginia |
| IKC | Virginia | Anthem Blue-Cross Blue-Shield of Virginia |
| IKD | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| IKE | Pennsylvania | Independence Blue-Cross of Philadelphia and Southeastern Pennsylvania |
| IKF | Pennsylvania | Independence Blue-Cross of Philadelphia and Southeastern Pennsylvania |
| IKG | - | Unallocated/Not Assigned |
| IKH | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| IKI | Florida | Florida-Blue |
| IKJ | - | Unallocated/Not Assigned |
| IKK | Michigan | Blue-Cross Blue-Shield of Michigan |
| IKL | Virginia | Anthem Blue-Cross Blue-Shield of Virginia |
| IKM | - | Unallocated/Not Assigned |
| IKN | - | Unallocated/Not Assigned |
| IKO | Delaware | Highmark Blue-Cross Blue-Shield of Delaware |
| IKP | - | Unallocated/Not Assigned |
| IKQ | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| IKR | Missouri | Anthem Blue-Cross Blue-Shield of Missouri |
| IKS | California | Blue-Shield of California |
| IKT | Kentucky | Anthem Blue-Cross Blue-Shield of Kentucky |
| IKU | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IKV | Michigan | Blue-Cross Blue-Shield of Michigan |
| IKW | - | Unallocated/Not Assigned |
| IKX | Michigan | Blue-Cross Blue-Shield of Michigan |
| IKY | Nebraska | Blue-Cross Blue-Shield of Nebraska |
| IKZ | - | Unallocated/Not Assigned |
| ILA | New York | Empire Blue-Cross Blue-Shield of New York |
| ILB | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| ILC | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| ILD | Michigan | Blue-Cross Blue-Shield of Michigan |
| ILE | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| ILF | Alabama | Blue-Cross Blue-Shield of Alabama |
| ILG | California | Blue-Shield of California |
| ILH | California | Anthem Blue-Cross |
| ILI | - | Unallocated/Not Assigned |
| ILJ | Wisconsin | Anthem Blue-Cross Blue-Shield of Wisconsin |
| ILK | Oregon/Idaho/Utah/Washington | Regence Blue-Cross Blue-Shield |
| ILL | California | Anthem Blue-Cross |
| ILM | - | Unallocated/Not Assigned |
| ILN | - | Unallocated/Not Assigned |
| ILO | Wisconsin | Anthem Blue-Cross Blue-Shield of Wisconsin |
| ILP | Kansas City | Blue-Cross Blue-Shield of Kansas City |
| ILQ | - | Unallocated/Not Assigned |
| ILR | - | Unallocated/Not Assigned |
| ILS | Alaska | Premera Blue-Cross Blue-Shield of Alaska |
| ILT | Illinois | Blue-Cross Blue-Shield of Illinois |
| ILU | - | Unallocated/Not Assigned |
| ILV | Alabama | Blue-Cross Blue-Shield of Alabama |
| ILW | California | Blue-Shield of California |
| ILX | Alabama | Blue-Cross Blue-Shield of Alabama |
| ILY BCBS Prefix | California | Anthem Blue-Cross |
| ILZ | Michigan | Blue-Cross Blue-Shield of Michigan |
| IMA | New York | Excellus Blue-Cross Blue-Shield of New York |
| IMB | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| IMC | Virginia | Anthem Blue-Cross Blue-Shield of Virginia |
| IMD | - | Unallocated/Not Assigned |
| IME | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| IMF | Oregon/Idaho/Utah/Washington | Regence Blue-Cross Blue-Shield |
| IMG | Oregon/Idaho/Utah/Washington | Regence Blue-Cross Blue-Shield |
| IMH | Colorado | Anthem Blue-Cross Blue-Shield of Colorado |
| IMI | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| IMJ | Missouri | Anthem Blue-Cross Blue-Shield of Missouri |
| IMK | Maine | Anthem Blue-Cross Blue-Shield of Maine |
| IML | - | Unallocated/Not Assigned |
| IMM | New York (Western) | Blue-Cross Blue-Shield of Western New York |
| IMN | - | Unallocated/Not Assigned |
| IMO | - | Unallocated/Not Assigned |
| IMP | - | Unallocated/Not Assigned |
| IMQ | Tennessee | Blue-Cross Blue-Shield of Tennessee |
| IMR | Alabama | Blue-Cross Blue-Shield of Alabama |
| IMS | Kentucky | Anthem Blue-Cross Blue-Shield of Kentucky |
| IMT | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| IMU | Louisiana | Blue-Cross Blue-Shield of Louisiana |
| IMV | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| IMW | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| IMX | Missouri | Anthem Blue-Cross Blue-Shield of Missouri |
| IMY | South Carolina | Blue-Cross Blue-Shield of South Carolina |
| IMZ | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| INA | Kentucky | Anthem Blue-Cross Blue-Shield of Kentucky |
| INB | Alaska | Premera Blue-Cross of Alaska |
| INC | California | Anthem Blue-Cross |
| IND | North Carolina | Blue-Cross Blue-Shield of North Carolina |
| INE | South Carolina | Blue-Cross Blue-Shield of South Carolina |
| INF | - | Unallocated/Not Assigned |
| ING | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| INH | - | Unallocated/Not Assigned |
| INI | Delaware | Highmark Blue-Cross Blue-Shield of Delaware |
| INJ | Kentucky | Anthem Blue-Cross Blue-Shield of Kentucky |
| INK | California | Anthem Blue-Cross |
| INL | Tennessee | Blue-Cross Blue-Shield of Tennessee |
| INM | - | Unallocated/Not Assigned |
| INN | - | Unallocated/Not Assigned |
| INO | California | Blue-Shield of California |
| INP | North Carolina | Blue-Cross Blue-Shield of North Carolina |
| INQ | Oregon/Idaho/Utah/Washington | Regence Blue-Cross Blue-Shield |
| INR | Indiana | Anthem Blue-Cross Blue-Shield of Indiana |
| INS | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| INT | Virginia | Anthem Blue-Cross Blue-Shield of Virginia |
| INU | - | Unallocated/Not Assigned |
| INV | South Carolina | Blue-Cross Blue-Shield of South Carolina |
| INW | Pennsylvania | Independence Blue-Cross of Philadelphia and Southeastern Pennsylvania |
| INX | - | Unallocated/Not Assigned |
| INY | California | Anthem Blue-Cross |
| INZ | - | Unallocated/Not Assigned |
| IOA | - | Unallocated/Not Assigned |
| IOB | Tennessee | Blue-Cross Blue-Shield of Tennessee |
| IOC | California | Blue-Shield of California |
| IOD | Michigan | Blue-Cross Blue-Shield of Michigan |
| IOE | New York | Empire Blue-Cross Blue-Shield of New York |
| IOF | California | Blue-Shield of California |
| IOG | New York (Northeastern) | Blue-Shield of Northeastern New York |
| IOH | - | Unallocated/Not Assigned |
| IOI | Michigan | Blue-Cross Blue-Shield of Michigan |
| IOJ | Michigan | Blue-Cross Blue-Shield of Michigan |
| IOK | - | Unallocated/Not Assigned |
| IOL | Michigan | Blue-Cross Blue-Shield of Michigan |
| IOM | Michigan | Blue-Cross Blue-Shield of Michigan |
| ION | Florida | Florida-Blue |
| IOO | Michigan | Blue-Cross Blue-Shield of Michigan |
| IOP | New York (Western) | Blue-Cross Blue-Shield of Western New York |
| IOQ | Michigan | Blue-Cross Blue-Shield of Michigan |
| IOR | South Carolina | Blue-Cross Blue-Shield of South Carolina |
| IOS | North Carolina | Blue-Cross Blue-Shield of North Carolina |
| IOT | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| IOU | Louisiana | Blue-Cross Blue-Shield of Louisiana |
| IOV | - | Unallocated/Not Assigned |
| IOW | - | Unallocated/Not Assigned |
| IOX | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| IOY | South Carolina | Blue-Cross Blue-Shield of South Carolina |
| IOZ | California | Blue-Shield of California |
| IPA | Virginia | Anthem Blue-Cross Blue-Shield of Virginia |
| IPB | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| IPC | - | Unallocated/Not Assigned |
| IPD | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| IPE | California | Blue-Shield of California |
| IPF | - | Unallocated/Not Assigned |
| IPG | Virginia | Anthem Blue-Cross Blue-Shield of Virginia |
| IPH | Kansas | Blue-Cross Blue-Shield of Kansas |
| IPI | - | Unallocated/Not Assigned |
| IPJ | - | Unallocated/Not Assigned |
| IPK | California | Blue-Shield of California |
| IPL | Kansas City | Blue-Cross Blue-Shield of Kansas City |
| IPM | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| IPN | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| IPO | - | Unallocated/Not Assigned |
| IPP | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IPQ | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| IPR | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| IPS | California | Blue-Shield of California |
| IPT | Illinois | Blue-Cross Blue-Shield of Illinois |
| IPU | Idaho | Blue-Cross of Idaho |
| IPV | Michigan | Blue-Cross Blue-Shield of Michigan |
| IPW | Oregon/Idaho/Utah/Washington | Regence Blue-Cross Blue-Shield |
| IPX | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| IPY | New York (Western) | Blue-Cross Blue-Shield of Western New York |
| IPZ | Rhode Island | Blue-Cross Blue-Shield of Rhode Island |
| IQA | - | Unallocated/Not Assigned |
| IQB | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IQC | Pennsylvania | Capital Blue-Cross of Pennsylvania |
| IQD | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IQE | Tennessee | Blue-Cross Blue-Shield of Tennessee |
| IQF | Tennessee | Blue-Cross Blue-Shield of Tennessee |
| IQG | Indiana | Anthem Blue-Cross Blue-Shield of Indiana |
| IQH | Kentucky | Anthem Blue-Cross Blue-Shield of Kentucky |
| IQI | Missouri | Anthem Blue-Cross Blue-Shield of Missouri |
| IQJ | Virginia | Anthem Blue-Cross Blue-Shield of Virginia |
| IQK | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IQL | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IQM | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IQN | Louisiana | Blue-Cross Blue-Shield of Louisiana |
| IQO | California | Anthem Blue-Cross |
| IQP | - | Unallocated/Not Assigned |
| IQQ | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IQR | Wisconsin | Anthem Blue-Cross Blue-Shield of Wisconsin |
| IQS | Pennsylvania | Independence Blue-Cross of Philadelphia and Southeastern Pennsylvania |
| IQT | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| IQU | Michigan | Blue-Cross Blue-Shield of Michigan |
| IQV | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IQW | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IQX | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IQY | South Carolina | Blue-Cross Blue-Shield of South Carolina |
| IQZ | - | Unallocated/Not Assigned |
| IRA | New Jersey | Horizon Blue-Cross Blue-Shield of New Jersey |
| IRB | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| IRC | Colorado | Anthem Blue-Cross Blue-Shield of Colorado |
| IRD | - | Unallocated/Not Assigned |
| IRE | - | Unallocated/Not Assigned |
| IRF | - | Unallocated/Not Assigned |
| IRG | Louisiana | Blue-Cross Blue-Shield of Louisiana |
| IRH | - | Unallocated/Not Assigned |
| IRI | Rhode Island | Blue-Cross Blue-Shield of Rhode Island |
| IRJ | South Carolina | Blue-Cross Blue-Shield of South Carolina |
| IRK | Alabama | Blue-Cross Blue-Shield of Alabama |
| IRL | - | Unallocated/Not Assigned |
| IRM | Kansas City | Blue-Cross Blue-Shield of Kansas City |
| IRN | - | Unallocated/Not Assigned |
| IRO | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| IRP | Florida | Florida-Blue |
| IRQ | Florida | Florida-Blue |
| IRR | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| IRS | Florida | Florida-Blue |
| IRT | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| IRU | Connecticut | Anthem Blue-Cross Blue-Shield of Connecticut |
| IRV | - | Unallocated/Not Assigned |
| IRW | California | Blue-Shield of California |
| IRX | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| IRY | Pennsylvania | Independence Blue-Cross of Philadelphia and Southeastern Pennsylvania |
| IRZ | California | Anthem Blue-Cross |
| ISA | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| ISB | Alaska | Premera Blue-Cross Blue-Shield of Alaska |
| ISC | New Jersey | Horizon Blue-Cross Blue-Shield of New Jersey |
| ISD | Arizona | Blue-Cross Blue-Shield of Arizona |
| ISE | Virginia | Anthem Blue-Cross Blue-Shield of Virginia |
| ISF | - | Unallocated/Not Assigned |
| ISG | - | Unallocated/Not Assigned |
| ISH | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| ISI | California | Blue-Shield of California |
| ISJ | Pennsylvania | Independence Blue-Cross of Philadelphia and Southeastern Pennsylvania |
| ISK | Kentucky | Anthem Blue-Cross Blue-Shield of Kentucky |
| ISL | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| ISM | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| ISN | Idaho | Blue-Cross of Idaho |
| ISO | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| ISP | Wisconsin | Anthem Blue-Cross Blue-Shield of Wisconsin |
| ISQ | Kansas City | Blue-Cross Blue-Shield of Kansas City |
| ISR | - | Unallocated/Not Assigned |
| ISS | Missouri | Anthem Blue-Cross Blue-Shield of Missouri |
| IST | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| ISU | Idaho | Blue-Cross of Idaho |
| ISV | - | Unallocated/Not Assigned |
| ISW | Idaho | Blue-Cross of Idaho |
| ISX | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| ISY | - | Unallocated/Not Assigned |
| ISZ | Idaho | Blue-Cross of Idaho |
| ITA | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| ITB | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| ITC | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| ITD | Pennsylvania | Independence Blue-Cross of Philadelphia and Southeastern Pennsylvania |
| ITE | North Carolina | Blue-Cross Blue-Shield of North Carolina |
| ITF | Michigan | Blue-Cross Blue-Shield of Michigan |
| ITG | - | Unallocated/Not Assigned |
| ITH | Pennsylvania | Capital Blue-Cross of Pennsylvania |
| ITI | - | Unallocated/Not Assigned |
| ITJ | - | Unallocated/Not Assigned |
| ITK | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| ITL | - | Unallocated/Not Assigned |
| ITM | Michigan | Blue-Cross Blue-Shield of Michigan |
| ITN | - | Unallocated/Not Assigned |
| ITO | New York (Northeastern) | Blue-Shield of Northeastern New York |
| ITP | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| ITQ | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| ITR | New York | Empire Blue-Cross Blue-Shield of New York |
| ITS | Arkansas | Arkansas Blue-Cross Blue-Shield |
| ITT | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| ITU | Oregon/Idaho/Utah/Washington | Regence Blue-Cross Blue-Shield |
| ITV | - | Unallocated/Not Assigned |
| ITW | Illinois | Blue-Cross Blue-Shield of Illinois |
| ITX | Oregon/Idaho/Utah/Washington | Regence Blue-Cross Blue-Shield |
| ITY | Pennsylvania | Independence Blue-Cross of Philadelphia and Southeastern Pennsylvania |
| ITZ | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IUA | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| IUB | Connecticut | Anthem Blue-Cross Blue-Shield of Connecticut |
| IUC | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| IUD | - | Unallocated/Not Assigned |
| IUE | New York | Empire Blue-Cross Blue-Shield of New York |
| IUF | Missouri | Anthem Blue-Cross Blue-Shield of Missouri |
| IUG | Alaska | Premera Blue-Cross Blue-Shield of Alaska |
| IUH | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| IUI | Rhode Island | Blue-Cross Blue-Shield of Rhode Island |
| IUJ | - | Unallocated/Not Assigned |
| IUK | Louisiana | Blue-Cross Blue-Shield of Louisiana |
| IUL | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| IUM | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| IUN | - | Unallocated/Not Assigned |
| IUO | New York | Empire Blue-Cross Blue-Shield of New York |
| IUP | Connecticut | Anthem Blue-Cross Blue-Shield of Connecticut |
| IUQ | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| IUR | Pennsylvania | Independence Blue-Cross of Philadelphia and Southeastern Pennsylvania |
| IUS | Pennsylvania | Independence Blue-Cross of Philadelphia and Southeastern Pennsylvania |
| IUT | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| IUU | - | Unallocated/Not Assigned |
| IUV | Oregon/Idaho/Utah/Washington | Regence Blue-Cross Blue-Shield |
| IUW | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| IUX | - | Unallocated/Not Assigned |
| IUY | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IUZ | - | Unallocated/Not Assigned |
| IVA | - | Unallocated/Not Assigned |
| IVB | Michigan | Blue-Cross Blue-Shield of Michigan |
| IVC | Kansas City | Blue-Cross Blue-Shield of Kansas City |
| IVD | - | Unallocated/Not Assigned |
| IVE | California | Blue-Shield of California |
| IVF | Tennessee | Blue-Cross Blue-Shield of Tennessee |
| IVG | - | Unallocated/Not Assigned |
| IVH | Rhode Island | Blue-Cross Blue-Shield of Rhode Island |
| IVI | Louisiana | Blue-Cross Blue-Shield of Louisiana |
| IVJ | Wisconsin | Anthem Blue-Cross Blue-Shield of Wisconsin |
| IVK | Mississippi | Blue-Cross Blue-Shield of Mississippi |
| IVL | - | Unallocated/Not Assigned |
| IVM | - | Unallocated/Not Assigned |
| IVN | Tennessee | Blue-Cross Blue-Shield of Tennessee |
| IVO | - | Unallocated/Not Assigned |
| IVP | Michigan | Blue-Cross Blue-Shield of Michigan |
| IVQ | - | Unallocated/Not Assigned |
| IVR | Arizona | Blue-Cross Blue-Shield of Arizona |
| IVS | California | Anthem Blue-Cross |
| IVT | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| IVU | Florida | Florida-Blue |
| IVV | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| IVW | Wisconsin | Anthem Blue-Cross Blue-Shield of Wisconsin |
| IVX | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| IVY | Rhode Island | Blue-Cross Blue-Shield of Rhode Island |
| IVZ | Indiana | Anthem Blue-Cross Blue-Shield of Indiana |
| IWA BCBS Prefix | Indiana | Anthem Blue-Cross Blue-Shield of Indiana |
| IWB | - | Unallocated/Not Assigned |
| IWC | Virginia | Anthem Blue-Cross Blue-Shield of Virginia |
| IWD | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| IWE | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| IWF | New York | Empire Blue-Cross Blue-Shield of New York |
| IWG | New York | Excellus Blue-Cross Blue-Shield of New York |
| IWH | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| IWI | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IWJ | Indiana | Anthem Blue-Cross Blue-Shield of Indiana |
| IWK | Michigan | Blue-Cross Blue-Shield of Michigan |
| IWL | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IWM | - | Unallocated/Not Assigned |
| IWN | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| IWO | Missouri | Anthem Blue-Cross Blue-Shield of Missouri |
| IWP | Michigan | Blue-Cross Blue-Shield of Michigan |
| IWQ | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IWR | Connecticut | Anthem Blue-Cross Blue-Shield of Connecticut |
| IWS | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| IWT | Pennsylvania | Capital Blue-Cross of Pennsylvania |
| IWU | Virginia | Anthem Blue-Cross Blue-Shield of Virginia |
| IWV | Kansas City | Blue-Cross Blue-Shield of Kansas City |
| IWW | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| IWX | New York (Western) | Blue-Cross Blue-Shield of Western New York |
| IWY | New York | Empire Blue-Cross Blue-Shield of New York |
| IWZ | Michigan | Blue-Cross Blue-Shield of Michigan |
| IXA | Arkansas | Arkansas Blue-Cross Blue-Shield |
| IXB | California | Blue-Shield of California |
| IXC | - | Unallocated/Not Assigned |
| IXD | - | Unallocated/Not Assigned |
| IXE | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| IXF | Indiana | Anthem Blue-Cross Blue-Shield of Indiana |
| IXG | Indiana | Anthem Blue-Cross Blue-Shield of Indiana |
| IXH | Indiana | Anthem Blue-Cross Blue-Shield of Indiana |
| IXI | Florida | Florida-Blue |
| IXJ | Indiana | Anthem Blue-Cross Blue-Shield of Indiana |
| IXK | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| IXL | California | Blue-Shield of California |
| IXM | California | Blue-Shield of California |
| IXN | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| IXO | California | Blue-Shield of California |
| IXP | Missouri | Anthem Blue-Cross Blue-Shield of Missouri |
| IXQ | South Carolina | Blue-Cross Blue-Shield of South Carolina |
| IXR | Michigan | Blue-Cross Blue-Shield of Michigan |
| IXS | - | Unallocated/Not Assigned |
| IXT | - | Unallocated/Not Assigned |
| IXU | Pennsylvania | Independence Blue-Cross of Philadelphia and Southeastern Pennsylvania |
| IXV | - | Unallocated/Not Assigned |
| IXW | Michigan | Blue-Cross Blue-Shield of Michigan |
| IXX | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| IXY | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| IXZ | - | Unallocated/Not Assigned |
| IYA | - | Unallocated/Not Assigned |
| IYB | Wisconsin | Anthem Blue-Cross Blue-Shield of Wisconsin |
| IYC | Pennsylvania | Independence Blue-Cross of Philadelphia and Southeastern Pennsylvania |
| IYD | Pennsylvania | Capital Blue-Cross of Pennsylvania |
| IYE | - | Unallocated/Not Assigned |
| IYF | - | Unallocated/Not Assigned |
| IYG | Florida | Florida-Blue |
| IYH | Kentucky | Anthem Blue-Cross Blue-Shield of Kentucky |
| IYI | Michigan | Blue-Cross Blue-Shield of Michigan |
| IYJ | Kansas City | Blue-Cross Blue-Shield of Kansas City |
| IYK | - | Unallocated/Not Assigned |
| IYL | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IYM | - | Unallocated/Not Assigned |
| IYN | Alaska | Premera Blue-Cross of Alaska |
| IYO | - | Unallocated/Not Assigned |
| IYP | Colorado | Anthem Blue-Cross Blue-Shield of Colorado |
| IYQ | South Carolina | Blue-Cross Blue-Shield of South Carolina |
| IYR | Florida | Florida-Blue |
| IYS | - | Unallocated/Not Assigned |
| IYT | - | Unallocated/Not Assigned |
| IYU | Michigan | Blue-Cross Blue-Shield of Michigan |
| IYV | Michigan | Blue-Cross Blue-Shield of Michigan |
| IYW | Pennsylvania | Independence Blue-Cross of Philadelphia and Southeastern Pennsylvania |
| IYX | Michigan | Blue-Cross Blue-Shield of Michigan |
| IYY | Michigan | Blue-Cross Blue-Shield of Michigan |
| IYZ | Michigan | Blue-Cross Blue-Shield of Michigan |
| IZA | Alabama | Blue-Cross Blue-Shield of Alabama |
| IZB | Wisconsin | Anthem Blue-Cross Blue-Shield of Wisconsin |
| IZC | - | Unallocated/Not Assigned |
| IZD | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IZE | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| IZF | Pennsylvania | Independence Blue-Cross of Philadelphia and Southeastern Pennsylvania |
| IZG | Michigan | Blue-Cross Blue-Shield of Michigan |
| IZH | - | Unallocated/Not Assigned |
| IZI | Michigan | Blue-Cross Blue-Shield of Michigan |
| IZJ | Michigan | Blue-Cross Blue-Shield of Michigan |
| IZK | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| IZL | Michigan | Blue-Cross Blue-Shield of Michigan |
| IZM | Michigan | Blue-Cross Blue-Shield of Michigan |
| IZN | - | Unallocated/Not Assigned |
| IZO | Michigan | Blue-Cross Blue-Shield of Michigan |
| IZP | Idaho | Blue-Cross of Idaho |
| IZQ | - | Unallocated/Not Assigned |
| IZR | Michigan | Blue-Cross Blue-Shield of Michigan |
| IZS | Michigan | Blue-Cross Blue-Shield of Michigan |
| IZT | - | Unallocated/Not Assigned |
| IZU | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| IZV | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| IZW | Michigan | Blue-Cross Blue-Shield of Michigan |
| IZX | Michigan | Blue-Cross Blue-Shield of Michigan |
| IZY | Michigan | Blue-Cross Blue-Shield of Michigan |
| IZZ | - | Unallocated/Not Assigned |