Billing Reference
CMS-1500 Form Field Reference
Learn what goes in each box of the CMS-1500 (02-12) claim form with a printable, training-only reference card. Patient and insured info, diagnoses, service lines, and billing totals — explained box by box.
Read before you print
This is a training reference, not a submittable claim form.
The official CMS-1500 (02-12) form must be OCR-printed on red dropout stock to be scannable. A printout from this page will not be accepted by payers.
Most practices submit claims electronically as an 837 transaction through a clearinghouse or their practice management system. Use this reference to learn what each box means and to train staff.
How to use this card
Walk the boxes left to right, top to bottom. Each entry shows the box number, what belongs there, and a realistic example.
Pair it with your clearinghouse or billing software, which maps these same fields onto the electronic 837 claim automatically.
CMS-1500 Field Reference
CMS-1500 (02-12) — what goes in each box.
CMS-1500 (02-12) Claim Form
Field-by-field reference
A quick guide to the most-used boxes on the CMS-1500 claim form. For training and reference only.
Patient & insured information
Identifies the patient and the policyholder (who may be different people).
- Box 1aInsured’s ID number
The member/policy ID from the insurance card.
Example: ABC123456789
- Box 2Patient’s name
Last, first, middle initial of the person receiving care.
Example: Doe, Jane M
- Box 3Patient’s date of birth and sex
DOB in MM DD CCYY format plus the patient’s sex.
Example: 04 / 15 / 1990
- Box 4Insured’s name
The policyholder, if different from the patient.
Example: Doe, John M
- Box 5Patient’s address
Street, city, state, ZIP, and telephone.
Example: 123 Main St, Anytown, ST 00000
- Box 6Patient relationship to insured
Self, spouse, child, or other.
Example: Self
Diagnosis
Reports the clinical diagnoses that justify the services billed on this claim.
- Box 21Diagnosis or nature of illness
Up to 12 ICD-10-CM diagnosis codes (A–L), lettered in priority order.
Example: F41.1 (Generalized anxiety disorder)
- Box 22Resubmission code
Original reference number when resubmitting a corrected claim.
Example: Leave blank on first submission
- Box 23Prior authorization number
Authorization or referral number from the payer, if required.
Example: AUTH-987654
Service line items (box 24)
Each row describes one service, its date, place, code, and charge.
- Box 24aDate(s) of service
From and to dates in MM DD CCYY format.
Example: 07 01 2026 – 07 01 2026
- Box 24bPlace of service code
Two-digit code for where the service happened (e.g., 11 = office, 02 = telehealth).
Example: 11
- Box 24dCPT/HCPCS and modifiers
Procedure code plus any modifiers that adjust the service.
Example: 90834 (psychotherapy, 45 min)
- Box 24eDiagnosis pointer
Letter(s) from box 21 that link this service to the diagnosis.
Example: A
- Box 24fCharges
Billed charge for the service on this line.
Example: 150.00
- Box 24gDays or units
Number of units (typically 1 per session for timed psychotherapy).
Example: 1
- Box 24jRendering provider NPI
National Provider Identifier of the clinician who rendered the service.
Example: 1234567893
Billing provider & totals
Identifies who is billing and summarizes the financial totals.
- Box 25Federal Tax ID (EIN/SSN)
Practice tax ID with the qualifier checked (EIN or SSN).
Example: XX-XXXXXXX
- Box 26Patient’s account number
Optional internal ID you use to track the patient.
Example: PT-0042
- Box 27Accept assignment
Whether the provider accepts assignment of benefits (Yes/No).
Example: YES
- Box 28Total charge
Sum of all line-item charges (box 24f).
Example: 150.00
- Box 29Amount paid
Any amount already collected from the patient.
Example: 0.00
- Box 30Balance due
Total charge minus amount paid.
Example: 150.00
- Box 31Signature of provider
Rendering provider signature (or on-file signature indicator) and date.
Example: Signed + date
- Box 32Service facility location
Name, address, and NPI where the service was rendered (if different from billing).
Example: Same as box 33
- Box 33Billing provider info
Billing practice name, address, NPI, and phone number.
Example: Practice name + NPI + phone
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Open toolWhat this reference supports
The CMS-1500 is the standard paper claim form, but almost no solo practice submits it on paper. Understanding the fields still matters: they map directly onto the electronic 837 transaction your clearinghouse sends, and knowing them helps you read rejections and train new staff.
This card walks the most-used boxes with plain-language descriptions and realistic examples, so a new biller or clinician can see how a therapy session becomes a claim.
Use it for situations like
- Onboarding a new biller or front-desk staff member.
- Decoding an payer rejection that cites a specific box number.
- Mapping your EHR fields onto the 837 equivalents before going live with a clearinghouse.
FAQ
Questions therapists ask before using this calculator
Can I print this and submit it as a claim?
No. This is a training reference, not a submittable claim form. The official CMS-1500 (02-12) must be OCR-printed on red dropout stock, and most payers require electronic 837 submission through a clearinghouse or practice management system.
What is the CMS-1500 form?
The CMS-1500 is the standard paper claim form healthcare providers use to bill insurance. The current version is CMS-1500 (02-12), maintained by the NUCC. Mental health providers most often submit it electronically as an 837 transaction.
Which boxes matter most for therapy billing?
For outpatient mental health, the highest-stakes boxes are 21 (diagnosis codes), 24b (place of service, e.g., 02 for telehealth), 24d (CPT code and modifiers), 24j (rendering provider NPI), and 33 (billing provider info).
Where do the diagnosis codes go?
ICD-10-CM diagnosis codes go in box 21, lettered A through L by priority. Each service line then references the relevant letter(s) in box 24e (the diagnosis pointer) to link the service to the diagnosis it supports.
How should I actually submit claims?
Use a clearinghouse or an EHR/practice management system that produces an electronic 837. It maps these same fields automatically, validates the claim before submission, and avoids the red-ink printing requirement.