CMS-1500 instructions — boxes 1 to 33
A field-by-field reference for form version 02/12, written against NUCC manual 13.0 7/25. Use it beside the [claim checker](/check).
Last reviewed against the NUCC 1500 Reference Instruction Manual (v13.0 7/25) and CMS Pub 100-04 Ch. 26 on .
How do I fill out a CMS-1500?
Use form version 02/12. Enter patient, insured, provider, diagnosis (box 21, indicator 0 for ICD-10-CM, no decimals), and up to six service lines (box 24). Point each line’s diagnosis letters in 24E at codes in 21. Complete billing provider (33/33a) with a 9-digit ZIP. Then run the checker before you submit.
How to use this page
Each section below names the box, what goes there, the format, whether it is required, and what commonly gets it rejected. Guidance is in our own words with citations — we do not republish the NUCC manual.
Check this box in the tool links jump to the checker. Payer-specific notes call out Medicare where CMS Chapter 26 differs from the general NUCC instructions.
Boxes 1–13 — payer, patient, insured, signatures
Box 1 — Insurance type. Mark the payer type (Medicare, Medicaid, TRICARE, CHAMPVA, Group Health Plan, FECA Black Lung, Other).
Box 1a — Insured’s ID. ID as shown on the card. For Medicare, this is the MBI (11 characters; letters S, L, O, I, B, Z are never used).
Box 2 — Patient name. Last, First, Middle Initial. No titles.
Box 3 — Patient DOB and sex. 8-digit date only (MMDDYYYY). Wrong-format DOB is a common unprocessable claim.
Box 4 — Insured’s name. When box 6 is Self, this should match box 2.
Box 5 — Patient address. Street, city, state, ZIP, phone.
Box 6 — Patient relationship to insured. Self, Spouse, Child, or Other.
Box 7 — Insured’s address. Complete when different from patient, or as required by the payer.
Box 8 — Reserved for NUCC use. Leave blank on the 02/12 form (formerly patient status).
Box 9 / 9a / 9d — Other insured. Complete when there is another plan (see box 11d). 9b and 9c are reserved — leave blank.
Box 10a–10c — Condition related to. Employment / auto accident (with state) / other accident — Yes or No each.
Box 10d — Claim codes. Designated by NUCC (live field, not reserved).
Box 11 — Insured’s policy group or FECA number. Medicare: this item must be completed; if no primary payer, enter the word NONE.
Box 11a — Insured’s DOB and sex. 8-digit DOB only.
Box 11b — Other claim ID. Qualifier (often Y4) plus value. Not a date field and not reserved.
Box 11c — Insurance plan name or program name.
Box 11d — Another health benefit plan? Yes/No. Yes requires boxes 9 / 9a / 9d.
Box 12 — Patient’s or authorized person’s signature. "Signature on File", "SOF", or a legal signature. A date is required only with a legal signature.
Box 13 — Insured’s or authorized person’s signature. Same signature options; there is no date field on the 02/12 form.
Boxes 14–23 — dates, referring provider, resubmission
Box 14 — Date of current illness, injury, or pregnancy (LMP). 6- or 8-digit date with qualifier (431 onset, 484 LMP).
Box 15 — Other date. 6 or 8 digits with a qualifier. Medicare: leave blank.
Box 16 — Dates patient unable to work. From–to, 6 or 8 digits.
Box 17 — Name of referring / ordering / supervising provider. Qualifier to the left of the name: DN referring, DK ordering, DQ supervising. No periods or commas in the name.
Box 17a — Other ID# (shaded). Qualifiers 0B, 1G, G2, or LU (supervising only).
Box 17b — NPI. 10 digits with valid check digit. PECOS enrollment is not checked by this site.
Box 18 — Hospitalization dates. From–to when related to current services.
Box 19 — Additional claim information. Designated by NUCC; free text as needed (for example unlisted-procedure narrative).
Box 20 — Outside lab. Yes/No and charges when applicable.
Box 22 — Resubmission code and original reference. 7 replacement, 8 void/cancel — not for original claims. Medicare: leave blank.
Box 23 — Prior authorization number. Also used for referral / mammography certification / CLIA. No hyphens or spaces. One condition only.
Box 21 — Diagnosis
Enter the ICD indicator in the upper right of the field: 0 for ICD-10-CM, 9 for ICD-9-CM.
List up to 12 diagnosis codes in lines A–L. Do not include the decimal point — it is implied. Do not put narrative descriptions in this field. Use the greatest level of specificity. Relate lines A–L to service lines via box 24E.
Do not list an external-cause code (V00–Y99) first at 21A. Do not mix ICD-9 and ICD-10 on one claim. More than 12 diagnoses requires splitting the claim.
Box 24 — Service lines (six lines)
Each claim form holds six service lines (24A–24J). Need more? Use a second claim form.
24A — Dates of service. The paper field is sized for MMDDYY (2-digit year). CMS Chapter 26 also permits 8-digit dates. Grouping across days is allowed only for consecutive days with identical POS, procedure, charge, and provider — and days must match units in 24G.
24B — Place of service. Two-digit code from the CMS Place of Service Code Set (public domain).
24C — EMG. Emergency indicator when applicable.
24D — Procedures, services, or supplies. CPT or HCPCS code plus up to four 2-character modifiers. This site checks format only. CPT code descriptions are copyrighted by the AMA; we do not display or look them up.
24E — Diagnosis pointer. Letters A–L referring to box 21. No commas. NUCC allows up to four letters; Medicare allows only one per line.
24F — Charges. No dollar signs, commas, or negatives. Enter cents (`00` if whole dollars).
24G — Days or units.
24H — EPSDT / family plan.
24I / 24J — Rendering provider IDs. Non-NPI ID in the shaded area with qualifier in 24I; NPI in the unshaded area of 24J. Report only when different from 33a/33b.
Shaded supplemental area (top of the line): NDC and other supplemental data (qualifiers N4, ZZ, DI, CTR, JP/JO). No space between qualifier and code.
Boxes 25–33 — tax ID, totals, facility, billing provider
Box 25 — Federal tax ID. 9 digits; mark SSN or EIN.
Box 26 — Patient account number. No hyphens, left justified, max 14 characters.
Box 27 — Accept assignment. Exactly one box marked (Yes or No).
Box 28 — Total charge. Sum of all 24F lines. 7+2 digit field; no commas or dollar signs.
Box 29 — Amount paid. 6+2 digits (narrower than 28). Patient and/or other payers, covered services only.
Box 30 — Reserved for NUCC use. Leave blank (formerly balance due).
Box 31 — Physician or supplier signature and date. Signature on File / SOF accepted. Date may be 6-digit, 8-digit, or alphanumeric.
Box 32 / 32a — Service facility. Name, address, 9-digit ZIP without hyphen, NPI when different from billing. Required for all place-of-service codes since 1 January 2011. Box 32b is not to be reported.
Box 33 / 33a / 33b — Billing provider. Name, address, 9-digit ZIP, phone, NPI. Should always be completed. No punctuation in the address. Taxonomy qualifier on the 1500 is ZZ (not PXC). Medicare generally does not require 33b.
Payer variance
NUCC and Medicare disagree on several boxes (24E pointer count, box 15, box 22, and others). The checker lets you select a payer profile so Medicare rules are applied only when you ask for them. Your payer’s companion guide remains the authority for that payer.
Sources
- NUCC 1500 Health Insurance Claim Form Reference Instruction Manual, Version 13.0 7/25 (opens in a new tab) — National Uniform Claim Committee
- 1500 Claim Form (version 02/12) (opens in a new tab) — National Uniform Claim Committee
- Medicare Claims Processing Manual, Chapter 26 (Pub 100-04) (opens in a new tab) — Centers for Medicare & Medicaid Services
- Place of Service Code Set (opens in a new tab) — Centers for Medicare & Medicaid Services
Last reviewed against the NUCC 1500 Reference Instruction Manual (v13.0 7/25) and CMS Pub 100-04 Ch. 26 on .
cms1500.app is an independent resource operated by AdvancedCare USA Inc. It is not affiliated with, endorsed by, or connected to the Centers for Medicare & Medicaid Services, the National Uniform Claim Committee, the American Medical Association, or any insurance payer. The CMS-1500 form is maintained by the NUCC.