How many blocks in total are on the CMS 1500 claim form?

Editorial team Published on

The CMS-1500 claim form contains 33 numbered blocks (or boxes), numbered from 1 to 33.

  • Patient and Insurance Data: Blocks 1 through 13 cover demographic and insurance information.
  • Claim and Condition Details: Blocks 14 through 23 cover condition, treatment, and authorization details.
  • Service Lines: Block 24 includes six individual service lines (24A through 24J) for specific procedures and diagnosis codes.
  • Provider Billing Information: Blocks 25 through 33 capture provider identifiers, total charges, signatures, and facility location details.

You can review a full breakdown of the layout and box instructions using the CMS 1500 Claim Form Instructions Tool.

How many fields are in the CMS-1500 claim form?

The CMS-1500 claim form contains 33 numbered boxes (fields or items).

Form Breakdown

  • Boxes 1–13: Patient and insured information (demographics, insurance type, and relationship to the insured).
  • Boxes 14–33: Physician or supplier information (medical necessity, diagnosis codes, dates of service, and provider details).

What is entered in block 1 on the CMS-1500 claim form?

Block 1 on the CMS-1500 Claim Form Guide requires you to indicate the type of health insurance coverage applicable to the claim by placing an "X" or checkmark in the appropriate box.

Available Options in Block 1

You can only select one plan type. The choices include:

  • Medicare
  • Medicaid
  • TRICARE / CHAMPUS
  • CHAMPVA
  • Group Health Plan (commercial insurance, employer-sponsored plans)
  • FECA Black Lung
  • Other (covers commercial insurance, HMOs, auto accident liability, or workers' compensation)

What will cause a CMS-1500 claim to be rejected?

A CMS-1500 claim is typically rejected before processing due to missing, invalid, or inaccurate data fields.

Common Causes of CMS-1500 Rejections

  • Incorrect Patient or Insured Information: Mismatches or typos in the patient's name, date of birth (Box 3), or member/policy ID number (Box 1a) cause immediate front-end rejections.
  • Provider Identifier Errors: Leaving the National Provider Identifier (NPI) blank or entering an incorrect NPI for the rendering provider (Box 24J) or billing provider (Box 33a) halts the claim.
  • Invalid or Deleted Diagnosis Codes: Using an inactive, deleted, or insufficiently specific ICD-10 code in Box 21 violates medical necessity guidelines and results in an automatic rejection.
  • Missing Tax ID or Employer ID: Failing to include or mistyping the federal Tax ID or SSN in Box 25 triggers entity code rejections.
  • Missing Referring Provider Details: Leaving Box 17 blank when services or therapies require a referral or order from an attending or consulting doctor will stop the claim.
  • Incorrect Payer ID: Submitting the form using the wrong electronic payer ID prevents the clearinghouse or insurance carrier from routing the claim correctly.

How do I complete a CMS-1500 claim form?

To complete a CMS-1500 claim form, follow the official guidelines outlined in the CMS Claims Processing Manual to fill out patient, provider, and service details across the three main sections of the document.

Patient and Insured Information (Boxes 1–13)

  • Box 1 & 1a: Select the correct insurance type (e.g., Medicare, Medicaid, Group Health) and enter the insured's unique ID number.
  • Box 2–3: Enter the patient's full legal name (Last, First, Middle Initial), date of birth (MM/DD/YYYY format), and sex.
  • Box 4–7: Provide the insured's name, relationship to the patient, and complete mailing address.
  • Box 12 & 13: Enter "Signature on File" (SOF) or obtain the patient and insured signatures authorizing the release of medical data and assignment of benefits.

Provider and Clinical Details (Boxes 14–23)

  • Box 14–15: Enter the date of current illness, injury, or pregnancy alongside the appropriate qualifier.
  • Box 17: List the referring or ordering provider's name and their National Provider Identifier (NPI) in Box 17b.
  • Box 21: Enter the ICD-10 diagnosis codes using indicator "0" to denote the classification version.
  • Box 23: Input the prior authorization or referral number if required by the payer.

Service Lines and Billing Details (Boxes 24–33)

  • Box 24A–J: Detail each service line item separately, including dates of service, place of service code (e.g., 11 for office), CPT/HCPCS procedure codes, charges, units, and the rendering provider's NPI.
  • Box 25–28: Provide the provider's federal Tax ID (EIN or SSN), patient account number, total charges, and check whether you accept assignment.
  • Box 31–33: Sign and date the form, and supply the service facility location and billing provider's name, address, and NPI.

General Completion Tips

  • Use black ink only and type or print legibly without using highlighters or correction fluid.
  • Avoid special characters like dollar signs or dashes in financial fields unless specifically instructed by your payer guidelines.

How to complete a CMS 1500 claim form in 5 minutes!

9 related questions found

Which is entered in block 21 of the CMS 1500 claim?

Block 21 of the CMS-1500 claim form is used to enter the patient's ICD-10-CM diagnosis codes (or nature of illness/injury).

Key Details About Block 21

  • Codes Entered: Up to 12 diagnosis codes (labeled A through L) can be reported on a single claim.
  • First-Listed Code: Block 21A holds the primary or first-listed diagnosis, which is the main reason for the patient's visit or treatment.
  • Format: Decimal points are omitted from the codes because they are implied.
  • Pointers: The preprinted letters (A–L) next to each code link the diagnosis to specific services in Block 24E to prove medical necessity.

What is field 24 in CMS 1500 claim form?

Field 24 on the CMS-1500 Claim Form is the core Service Lines section used to list the specific medical procedures, services, or supplies provided to the patient.

This section contains six horizontal service rows, divided into sub-fields labeled 24A through 24J:

  • Field 24A (Dates of Service): The from and to dates when the service or treatment occurred.
  • Field 24B (Place of Service): A two-digit code indicating where the service was delivered (e.g., 11 for office, 21 for inpatient hospital).
  • Field 24C (Emergency): An indicator (often left blank or marked with a specific character if required) showing if the service was an emergency.
  • Field 24D (Procedures, Services, or Supplies): The CPT or HCPCS codes describing the treatment, alongside any required modifiers.
  • Field 24E (Diagnosis Pointer): A letter or number pointer (A, B, C, etc.) linking the service line to a specific diagnosis code listed in Box 21.
  • Field 24F (Charges): The total dollar charge for the specific procedure line.
  • Field 24G (Days or Units): The quantity or duration of the service provided (such as units of time or number of visits).
  • Field 24H (EPSDT/Family Planning): Situational indicator used for Early and Periodic Screening, Diagnostic, and Treatment services.
  • Field 24I (ID Qualifier): Qualifier denoting the type of provider ID used in the shaded supplemental areas.
  • Field 24J (Rendering Provider ID): The National Provider Identifier (NPI) of the specific healthcare professional who performed the service.

Which information is entered in the CMS 1500 block?

The CMS-1500 Claim Form requires specific patient, insurance, and provider data across its 33 numbered blocks.

Key CMS-1500 Blocks and Their Information

  • Block 1 & 1a: Type of health insurance coverage (Medicare, Medicaid, Private) and the insured's ID number.
  • Block 2: Patient's full name (last, first, middle initial).
  • Block 3: Patient's birth date (MM/DD/YYYY) and sex.
  • Block 4: Insured's name (if different from the patient).
  • Block 5: Patient's address and telephone number.
  • Block 9–9d: Other insured's name, policy/group number, and supplemental plan information (if secondary insurance exists).
  • Block 14: Date of current illness, injury, or pregnancy (LMP).
  • Block 17: Name of the referring provider or other source.
  • Block 21: Diagnosis codes (up to 12 ICD-10 codes) explaining medical necessity.
  • Block 24A–24J: Details of specific services, including dates of service, CPT/HCPCS procedure codes, charges, days/units, and rendering provider NPI.
  • Block 25: Federal Tax ID number (EIN) or Social Security Number (SSN) of the provider/supplier.
  • Block 31: Provider signature and date.
  • Block 33: Billing provider's name, address, phone number, and NPI.

What information goes into block 11 of a CMS claim form?

Block 11 of the CMS-1500 claim form requires the insured's policy number, group number, or FECA (Federal Employees' Compensation Act) number for the primary insurance.

Key Requirements for Block 11

  • Primary Insurance: Enter the policy or group number of the primary health plan that is primary to Medicare or the current payer.
  • No Other Insurance: If there is no primary or secondary insurance other than the main payer, enter the word "NONE" instead of leaving it blank. Leaving it blank can result in claim rejections due to coordination of benefits (COB) issues.
  • FECA Claims: For federal workers' compensation work-related conditions, enter the FECA number.

Related Sub-Blocks (11a–11d)

  • Block 11a: Insured's date of birth (in an 8-digit MMDDYYYY format) and sex/gender.
  • Block 11b: Other claim ID or employer/school name (often left blank or used for specific secondary identifiers depending on the payer guidelines).
  • Block 11c: Insurance plan name or program name of the primary insurance.
  • Block 11d: Indicator asking if there is another health benefit plan (marked Yes or No).

Which is entered in block 11c of the CMS 1500?

The name of the policyholder's commercial health insurance plan or program is entered in Block 11c of the CMS-1500 claim form.

Key Details for Block 11c

  • Content: Enter the complete primary insurance plan name, program name, or the nine-digit payer ID number if required by the specific payer.
  • Context: This field works alongside other fields in Section 11, where Block 11 captures the group number and Block 11a captures the policyholder's birth date and gender.