NPI, TIN, Taxonomy: Locating Fields on CMS-1500 & UB-04 Forms (Paper & Electronic)

Last Updated: June 4, 2026

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Navigating the intricate landscape of medical billing requires a precise understanding of key identifiers like the NPI, TIN, and Taxonomy. These seemingly small details are the backbone of compliant claims processing, dictating whether a provider gets reimbursed accurately and on time. Misplacing a digit or omitting a required code can lead to costly denials, delays, and administrative burdens. This comprehensive guide will meticulously detail the location and significance of these critical identifiers on both paper (CMS-1500 and UB-04) and electronic (837P and 837I) claim forms, equipping you with the knowledge to ensure flawless submission and maximize revenue cycle efficiency.

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This table provides a concise overview of where to locate NPI, TIN, and Taxonomy codes across various claim types and provider roles. Refer to the detailed breakdown below for in-depth explanations and electronic transaction specifics.

IdentifierClaim Form / TransactionProvider RolePaper Field / Electronic Loop & SegmentDescription / Key Rule
NPI (National Provider Identifier)CMS-1500 / 837PBilling ProviderPaper: Box 33a
Electronic: Loop 2010AA, NPI segment
Type 1 (Individual) or Type 2 (Organizational) NPI of the entity submitting the claim.
Rendering ProviderPaper: Box 24J
Electronic: Loop 2310B, NPI segment
Type 1 NPI of the individual who performed the service.
Referring ProviderPaper: Box 17b
Electronic: Loop 2310A, NPI segment
Type 1 NPI of the individual who referred the patient.
UB-04 / 837IBilling ProviderPaper: FL 56
Electronic: Loop 2010AA, NPI segment
Type 2 NPI of the institutional facility.
Attending PhysicianPaper: FL 76
Electronic: Loop 2310A, NPI segment
Type 1 NPI of the physician primarily responsible for the patient’s care.
Operating PhysicianPaper: FL 77
Electronic: Loop 2310C, NPI segment
Type 1 NPI of the physician who performed the surgical procedure.
TIN (Taxpayer Identification Number)CMS-1500 / 837PBilling ProviderPaper: Box 25 (SSN/EIN)
Electronic: Loop 2010AA, REF segment (G2)
Employer Identification Number (EIN) for organizations, or Social Security Number (SSN) for sole proprietors.
UB-04 / 837IBilling ProviderPaper: FL 04 (Provider ID)
Electronic: Loop 2010AA, REF segment (G2)
EIN of the institutional facility. Often referred to as the HIPAA TIN.
Taxonomy CodeCMS-1500 / 837PBilling ProviderPaper: Box 33b (qualifier ‘B3’)
Electronic: Loop 2010AA, PRV segment
Specific provider type/specialty. Required by some payers.
Rendering ProviderPaper: Box 24I (qualifier ‘B3’)
Electronic: Loop 2310B, PRV segment
Specific provider type/specialty of the rendering provider.
UB-04 / 837IBilling ProviderPaper: FL 81 (Remarks – if required)
Electronic: Loop 2010AA, PRV segment
Specific institutional provider type. Payer-specific requirements.
Attending/Operating PhysicianPaper: FL 76/77 (if required)
Electronic: Loop 2310A/C, PRV segment
Specific physician specialty. Payer-specific requirements.

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Detailed Breakdown: Locating NPI, TIN, and Taxonomy

The precise placement of NPI, TIN, and Taxonomy codes varies significantly between paper and electronic claims, and across different provider roles. Understanding these nuances is paramount for accurate claim submission.

CMS-1500 Form (Professional Claims) & 837P Electronic Transaction

Billing Provider (The Entity Submitting the Claim)

  • NPI:
    • Paper CMS-1500: Located in Box 33a. This is the NPI of the individual or organization billing for the services. If a group practice is billing, this will typically be the Type 2 (organizational) NPI. If a solo practitioner bills under their own name, it will be their Type 1 (individual) NPI.
    • Electronic 837P: You can find the billing provider’s NPI in Loop 2010AA, NPI segment (NM109). This loop identifies the billing provider’s name and address. The NPI is a critical data element within this segment, ensuring the payer correctly identifies the entity responsible for the claim.
  • TIN (Taxpayer Identification Number):
    • Paper CMS-1500: Located in Box 25. This field requires either the provider’s Employer Identification Number (EIN) or Social Security Number (SSN). For group practices or incorporated entities, the EIN is used. For sole proprietors, the SSN may be used, though an EIN is often preferred for business purposes.
    • Electronic 837P: The billing provider’s TIN (often an EIN) is found in Loop 2010AA, REF segment (G2 qualifier). This is the HIPAA TIN, essential for tax reporting and identifying the legal entity associated with the claim.
  • Taxonomy Code:
    • Paper CMS-1500: Located in Box 33b. This field is used to specify the billing provider’s specialty or classification. It must be preceded by the qualifier ‘B3’ (e.g., B3:207Q00000X). This field is not universally required but is increasingly requested by specific payers or for certain specialties.
    • Electronic 837P: The billing provider’s taxonomy code is found in Loop 2010AA, PRV segment (PRV03). The PRV01 element will typically be ‘BI’ (Billing Provider), and PRV02 will be ‘PXC’ (Provider Taxonomy Code).

Rendering Provider (The Individual Who Performed the Service)

  • NPI:
    • Paper CMS-1500: Located in Box 24J. This is always the Type 1 (individual) NPI of the healthcare professional who directly provided the service.
    • Electronic 837P: The rendering provider’s NPI is found in Loop 2310B, NPI segment (NM109). This loop specifically identifies the individual who rendered the service.
  • Taxonomy Code:
    • Paper CMS-1500: Located in Box 24I. Similar to the billing provider, this field specifies the rendering provider’s specialty, preceded by the ‘B3’ qualifier.
    • Electronic 837P: The rendering provider’s taxonomy code is found in Loop 2310B, PRV segment (PRV03). The PRV01 element will be ‘PE’ (Performing Provider), and PRV02 will be ‘PXC’.

Referring Provider (The Individual Who Referred the Patient)

  • NPI:
    • Paper CMS-1500: Located in Box 17b. This is the Type 1 NPI of the physician or other healthcare professional who referred the patient for the service.
    • Electronic 837P: The referring provider’s NPI is found in Loop 2310A, NPI segment (NM109). This loop is dedicated to identifying the referring provider.
  • Taxonomy Code:
    • Paper CMS-1500: Located in Box 17a. If required by the payer, the referring provider’s taxonomy code would be entered here, typically with a ‘B3’ qualifier.
    • Electronic 837P: The referring provider’s taxonomy code is found in Loop 2310A, PRV segment (PRV03). The PRV01 element will be ‘RF’ (Referring Provider), and PRV02 will be ‘PXC’.

(Imagine an annotated image of a CMS-1500 form here, with Boxes 17a, 17b, 24I, 24J, 25, 33a, and 33b clearly highlighted and labeled with their respective NPI, TIN, and Taxonomy fields.)

UB-04 Form (Institutional Claims) & 837I Electronic Transaction

Billing Provider (The Institutional Facility)

  • NPI:
    • Paper UB-04: Located in Field Locator (FL) 56. This is always the Type 2 (organizational) NPI of the institutional facility (e.g., hospital, skilled nursing facility) submitting the claim.
    • Electronic 837I: Similar to 837P, the billing provider’s NPI is found in Loop 2010AA, NPI segment (NM109). This loop identifies the institutional billing entity.
  • TIN (Taxpayer Identification Number):
    • Paper UB-04: Often found in FL 04 (Provider ID), though this field can also be used for other payer-specific identifiers. For tax purposes, the facility’s EIN is the primary identifier.
    • Electronic 837I: The billing provider’s TIN (EIN) is found in Loop 2010AA, REF segment (G2 qualifier). This is the HIPAA TIN for the institutional provider.
  • Taxonomy Code:
    • Paper UB-04: While there isn’t a dedicated box for taxonomy on the UB-04, it may be entered in FL 81 (Remarks) if required by a specific payer, often with a qualifier.
    • Electronic 837I: The billing provider’s taxonomy code is found in Loop 2010AA, PRV segment (PRV03). The PRV01 element will be ‘BI’ (Billing Provider), and PRV02 will be ‘PXC’.

Attending Physician (Primarily Responsible for Patient Care)

  • NPI:
    • Paper UB-04: Located in FL 76. This is the Type 1 NPI of the physician primarily responsible for the patient’s care during the reported service period.
    • Electronic 837I: The attending physician’s NPI is found in Loop 2310A, NPI segment (NM109). This loop is specifically for the attending provider.
  • Taxonomy Code:
    • Paper UB-04: If required, the attending physician’s taxonomy code might be entered in FL 76 (next to the NPI) or in FL 81 (Remarks).
    • Electronic 837I: The attending physician’s taxonomy code is found in Loop 2310A, PRV segment (PRV03). The PRV01 element will be ‘AT’ (Attending Provider), and PRV02 will be ‘PXC’.

Operating Physician (Performed Surgical Procedure)

  • NPI:
    • Paper UB-04: Located in FL 77. This is the Type 1 NPI of the physician who performed the principal surgical procedure.
    • Electronic 837I: The operating physician’s NPI is found in Loop 2310C, NPI segment (NM109). This loop is dedicated to the operating provider.
  • Taxonomy Code:
    • Paper UB-04: Similar to the attending physician, if required, the operating physician’s taxonomy code might be entered in FL 77 or FL 81.
    • Electronic 837I: The operating physician’s taxonomy code is found in Loop 2310C, PRV segment (PRV03). The PRV01 element will be ‘OP’ (Operating Provider), and PRV02 will be ‘PXC’.

Other Providers (Referring, Ordering, Service Facility)

  • Paper UB-04: FL 78, 79, and 80 are designated for “Other Provider” NPIs and identifiers, which could include referring or ordering physicians, or other service providers. Taxonomy codes for these roles would typically be in FL 81 if required.
  • Electronic 837I:
    • Referring Provider: Loop 2310B (NPI in NM109, Taxonomy in PRV segment with ‘RF’ qualifier).
    • Ordering Provider: Loop 2310D (NPI in NM109, Taxonomy in PRV segment with ‘OR’ qualifier).
    • Service Facility Location: Loop 2310E (NPI in NM109).

(Imagine an annotated image of a UB-04 form here, with FL 04, FL 56, FL 76, FL 77, FL 78, FL 79, FL 80, and FL 81 clearly highlighted and labeled with their respective NPI, TIN, and Taxonomy fields.)

Payer-Specific Nuances

While the general guidelines for NPI, TIN, and Taxonomy are standardized, individual payers may have specific requirements or preferences. For instance:

  • Some payers may require the rendering provider’s taxonomy code even if it’s not explicitly mandated by HIPAA for all claims.
  • Certain state Medicaid programs or managed care organizations might have unique qualifiers or specific formats for submitting taxonomy codes.
  • For institutional claims, some payers might require the billing provider’s taxonomy in a specific field other than FL 81 or a particular electronic segment.
  • Always consult the payer’s provider manual or contact their provider relations department for the most up-to-date and specific billing instructions.

Real-World Billing Scenarios & Patient Status Changes

Understanding how NPI, TIN, and Taxonomy apply in various clinical and administrative contexts is crucial for accurate billing.

Scenario 1: Group Practice with Multiple Rendering Providers

A patient visits a large orthopedic group for a knee injury. Dr. Smith (Orthopedic Surgeon) performs the initial evaluation, and Dr. Jones (Physical Therapist) provides follow-up therapy sessions. The group practice, “Elite Orthopedics,” submits the claim.

  • Billing Provider: Elite Orthopedics (Type 2 NPI in CMS-1500 Box 33a / 837P Loop 2010AA, NPI segment). Elite Orthopedics’ EIN (HIPAA TIN) in CMS-1500 Box 25 / 837P Loop 2010AA, REF segment (G2). Elite Orthopedics’ taxonomy (e.g., Orthopedic Surgery Group) in CMS-1500 Box 33b / 837P Loop 2010AA, PRV segment.
  • Rendering Provider (Dr. Smith): Dr. Smith’s Type 1 NPI in CMS-1500 Box 24J (for his services) / 837P Loop 2310B, NPI segment. Dr. Smith’s taxonomy (Orthopedic Surgeon) in CMS-1500 Box 24I / 837P Loop 2310B, PRV segment.
  • Rendering Provider (Dr. Jones): Dr. Jones’s Type 1 NPI in CMS-1500 Box 24J (for her services) / 837P Loop 2310B, NPI segment. Dr. Jones’s taxonomy (Physical Therapist) in CMS-1500 Box 24I / 837P Loop 2310B, PRV segment.

Scenario 2: Hospital Outpatient Service with Referring Physician

A patient is referred by their primary care physician, Dr. Lee, to “City General Hospital” for an outpatient MRI. The hospital bills for the technical component of the MRI.

  • Billing Provider: City General Hospital (Type 2 NPI in UB-04 FL 56 / 837I Loop 2010AA, NPI segment). Hospital’s EIN (HIPAA TIN) in UB-04 FL 04 / 837I Loop 2010AA, REF segment (G2). Hospital’s taxonomy (e.g., General Acute Care Hospital) in UB-04 FL 81 (if required) / 837I Loop 2010AA, PRV segment.
  • Referring Provider (Dr. Lee): Dr. Lee’s Type 1 NPI in UB-04 FL 78 (or other appropriate “Other Provider” field) / 837I Loop 2310B, NPI segment. Dr. Lee’s taxonomy (Family Medicine) in UB-04 FL 81 (if required) / 837I Loop 2310B, PRV segment.

Scenario 3: Inpatient Surgery with Attending and Operating Physicians

A patient undergoes an appendectomy at “County Medical Center.” Dr. Evans is the attending physician, and Dr. Chen performs the surgery.

  • Billing Provider: County Medical Center (Type 2 NPI in UB-04 FL 56 / 837I Loop 2010AA, NPI segment). Hospital’s EIN (HIPAA TIN) in UB-04 FL 04 / 837I Loop 2010AA, REF segment (G2).
  • Attending Physician (Dr. Evans): Dr. Evans’s Type 1 NPI in UB-04 FL 76 / 837I Loop 2310A, NPI segment. Dr. Evans’s taxonomy (e.g., Internal Medicine) in UB-04 FL 76 (if required) / 837I Loop 2310A, PRV segment.
  • Operating Physician (Dr. Chen): Dr. Chen’s Type 1 NPI in UB-04 FL 77 / 837I Loop 2310C, NPI segment. Dr. Chen’s taxonomy (e.g., General Surgery) in UB-04 FL 77 (if required) / 837I Loop 2310C, PRV segment.

Scenario 4: Patient Status Changes and Discharge

When a patient’s status changes, particularly upon discharge from an inpatient facility, the UB-04 form requires specific “Patient Status Codes” (FL 17). These codes indicate the patient’s disposition at the time of discharge (e.g., discharged to home, transferred to another facility, expired). Accurate NPIs, TINs, and Taxonomy codes remain critical for the billing facility and any subsequent facilities or providers involved in the patient’s care transition. Incorrect patient status codes, combined with missing or incorrect provider identifiers, can lead to denials or issues with continuity of care billing.

Common Denial Codes & Step-by-Step Appeal Instructions

Incorrect or missing NPI, TIN, or Taxonomy codes are frequent culprits behind claim denials. Here are common denial codes and a general appeal process:

Common Denial Codes

  • CO-16: Claim/service lacks information which is needed for adjudication, or has invalid information.
    • Cause: This is a broad denial, but often points to missing or incorrect NPIs, TINs, or Taxonomy codes for any of the involved providers (billing, rendering, referring, operating). It could also mean the NPI is valid but doesn’t match the provider’s name or specialty on file with the payer.
    • Solution: Verify all NPIs, TINs, and Taxonomy codes against the provider’s NPI registry entry and the payer’s enrollment records. Ensure the correct NPI type (Type 1 vs. Type 2) is used for each role.

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