HCFA-1500 Box 1a - Insured's ID Number

January 01, 2024
On the HCFA-1500 form, box 1a is designated for the insured's ID Number. This will normally be the insured id number for the subscriber of the claim. While not typical, some payers may assign unique identification numbers to each enrollee/dependent and require the specific number of the member receiving services instead of the insured's number. See the members insurance card and/or use an Eligibility check service to verify the information prior to populating.
In our example below, we populated box 1a with 'ABC12345678'. The formatting of the number will vary. Typically, spaces/hyphens are removed from the id number.

So far, we talked about what the insured's id number box on the HCFA form is and the information used to populate this location. In the next section, we'll briefly discuss the insured's id number box in relation to the X12 837 format.
In the X12 837 format, the insured's id number box information goes in the 2010BA Subscriber Name Loop - NM1 segment. More specifically, the HCFA Box 1a insured's id number data goes in the NM109, which is also known as the Subscriber Primary Identifier.
The example below shows the 2010BA Subscriber Name Loop - NM1 segment. In our sample, we have the value ABC12345678 for the NM109. For additional information on the X12 837 format, we strongly recommend consulting the official X12 materials.
Sample 837P (5010) - 2010BA - Subscriber Name
HCFA-1500 Form Box Locations
- HCFA-1500 Box 0 - Carrier Block
- HCFA-1500 Box 1 - Insurance Type
- HCFA-1500 Box 1a - Insured's ID Number [You are Here]
- HCFA-1500 Box 2 - Patient's Name
- HCFA-1500 Box 3 - Patient's Birth Date and Sex
- HCFA-1500 Box 4 - Insured's Name
- HCFA-1500 Box 5 - Patient's Address
- HCFA-1500 Box 6 - Patient Relationship to Insured
- HCFA-1500 Box 7 - Insured's Address
- HCFA-1500 Box 8 - Reserved For NUCC Use
- HCFA-1500 Box 9 - Other Insured's Name
- HCFA-1500 Box 9a - Other Insured's Policy or Group Number
- HCFA-1500 Box 9b - Reserved For NUCC Use
- HCFA-1500 Box 9c - Reserved For NUCC Use
- HCFA-1500 Box 9d - Insurance Plan Name or Program Name
- HCFA-1500 Box 10 - Is Patient's Condition Related To
- HCFA-1500 Box 10d - Claim Codes
- HCFA-1500 Box 11 - Insured's Policy Group or FECA Number
- HCFA-1500 Box 11a - Insured's Date of Birth and Sex
- HCFA-1500 Box 11b - Other Claim ID
- HCFA-1500 Box 11c - Insurance Plan Name or Program Name
- HCFA-1500 Box 11d - Is There Another Health Plan
- HCFA-1500 Box 12 - Patient's or Authorized Person's Signature
- HCFA-1500 Box 13 - Insured's or Authorized Person's Signature
- HCFA-1500 Box 14 - Date of Current Illness, Injury, Pregnancy (LMP)
- HCFA-1500 Box 15 - Other Date
- HCFA-1500 Box 16 - Dates Patient Unable to Work in Current Occupation
- HCFA-1500 Box 17 - Name of Referring Provider or Other Source
- HCFA-1500 Box 17a - Other ID
- HCFA-1500 Box 17b - NPI
- HCFA-1500 Box 18 - Hospitalization Dates Related to Current Services
- HCFA-1500 Box 19 - Additional Claim Information
- HCFA-1500 Box 20 - Outside Lab Charges
- HCFA-1500 Box 21 - Diagnosis or Nature of Illness or Injury
- HCFA-1500 Box 22 - Resubmission Code and Original Reference Number
- HCFA-1500 Box 23 - Prior Authorization Number
- HCFA-1500 Box 24a - Date(s) of Service
- HCFA-1500 Box 24b - Place of Service
- HCFA-1500 Box 24c - EMG
- HCFA-1500 Box 24d - Procedures, Services, or Supplies
- HCFA-1500 Box 24e - Diagnosis Pointer
- HCFA-1500 Box 24f - Charges
- HCFA-1500 Box 24g - Days or Units
- HCFA-1500 Box 24h - EPSDT/Family Plan
- HCFA-1500 Box 24i - Rendering Provider ID Qualifier
- HCFA-1500 Box 24j - Rendering Provider ID
- HCFA-1500 Box 25 - Federal Tax ID Number
- HCFA-1500 Box 26 - Patient's Account No.
- HCFA-1500 Box 27 - Accept Assignment
- HCFA-1500 Box 28 - Total Charge
- HCFA-1500 Box 29 - Amount Paid
- HCFA-1500 Box 30 - Rsvd for NUCC Use
- HCFA-1500 Box 31 - Signature of Physician or Supplier Including Degrees or Credentials
- HCFA-1500 Box 32 - Service Facility Location Information
Grab a sample of the HCFA-1500 claim form here - HCFA 02/12 Claim Form
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