Overview
Field 56 on the UB-04 claim form is designated for the National Provider Identifier (NPI) of the Billing Provider [1]. This field serves as the primary identification mechanism for the entity that is submitting the claim and seeking reimbursement for medical services rendered [1]. The NPI is a unique, 10-digit identification number mandated by HIPAA for healthcare providers in the United States [2]. According to CMS guidelines, the inclusion of the Billing Provider NPI became a mandatory requirement for all applicable claims submitted on or after May 23, 2008 [2].
The Billing Provider listed in this field is the entity that maintains the legal and financial responsibility for the services billed [1]. While other fields on the UB-04 form identify specific individuals, such as the Attending Provider or Operating Physician, Field 56 specifically identifies the organization or individual practitioner acting as the billing entity [1] [2]. For institutional claims, this is typically the hospital, skilled nursing facility, or home health agency [1]. Proper completion of this field is essential for the adjudication process, as payers use this number to link the claim to the provider's enrollment record, tax information, and contracted rate schedules [2].
When to Use
Field 56 is categorized as a required field for both inpatient and outpatient institutional claims [1]. It must be utilized every time a claim is submitted to a payer, including Medicare, Medicaid, and private insurance carriers, to ensure the billing entity is correctly identified [2]. The NPI entered here must correspond to the Billing Provider whose name and address appear in Field 01 of the UB-04 form [1].
This field is used specifically for the National Provider Identifier and should not be confused with legacy provider numbers or state-specific identifiers [2]. Under current CMS regulations, other provider identifiers that were previously used are no longer accepted in this specific field [2]. Failure to provide a valid, 10-digit NPI in this field will result in the immediate rejection of the claim by the clearinghouse or the payer's adjudication system, as it is a fundamental requirement for electronic and paper claim processing [2].
Step-by-Step Claim Example
To complete Field 56 correctly, the biller must follow a specific sequence to ensure the data aligns with the rest of the claim form and the provider's official registration [1].
- Identify the Billing Entity: Determine the correct legal entity responsible for the bill. For a hospital stay, this is the facility itself [1].
- Retrieve the NPI: Locate the 10-digit National Provider Identifier assigned to the billing entity. Ensure this is the NPI registered with the National Plan and Provider Enumeration System (NPPES) for the specific location or organization [2].
- Verify Field 01 Alignment: Ensure the name and address of the provider in Field 01 match the entity associated with the NPI being used in Field 56 [1].
- Enter the Data: Type the 10-digit NPI into Box 56. Do not include hyphens, spaces, or any other special characters [2].
- Cross-Reference with Field 57: Note that while Field 56 is required, Field 57 (Other Provider ID) is generally not used or ignored by CMS, as the NPI is the primary identifier [2].
- Review for Accuracy: Confirm the NPI is placed in the correct box (Field 56) and is not accidentally entered into Field 76 (Attending Provider) or Field 77 (Operating Physician), which require different NPIs [1].
Common Mistakes & Audit Red Flags
One of the most frequent errors regarding Field 56 is the "NPI Mismatch," where the NPI provided does not match the Billing Provider's name or Taxpayer Identification Number (TIN) on file with the payer [1] [2]. This discrepancy often triggers an immediate audit or claim denial. Another common mistake is entering a legacy provider number or a state-specific Medicaid ID instead of the NPI; CMS instructions explicitly state that the NPI has been the required identifier since 2008 [2].
Furthermore, entering data into Field 57 (Other Provider ID) can cause confusion, as CMS guidelines indicate that data entered in Field 57 will be ignored [2]. Providers should also be cautious not to leave Field 56 blank, as it is a mandatory field for all claim types [1]. Finally, using the NPI of the Attending Physician (found in Field 76) in the Billing Provider field (Field 56) is a significant error that will lead to payment being directed to the wrong entity or the claim being rejected for inconsistent data [1].
Related Codes/Fields
| Field | Title | Description |
|---|---|---|
| FL 01 | Billing Provider Name and Address | The name and location of the entity associated with the NPI in Field 56 [1]. |
| FL 57 | Other Provider ID | A legacy identifier field that is largely not used or ignored by CMS [2]. |
| FL 76 | Attending Provider | Identifies the individual physician with primary responsibility for the patient's care [1]. |
| FL 77 | Operating Physician | Identifies the individual who performed the principal procedure [1]. |
| FL 50 | Payer Name | The insurance carrier to whom the NPI and claim are being submitted [1]. |
References
[1] Maryland Medicaid — FL 56 — https://health.maryland.gov/mmcp/provider/Documents/ffs-billing/UB04-Hospital-Billing-Instructions%20%281%29.pdf
[2] CMS Chapter 25 — FL 56 — https://www.cms.gov/regulations-and-guidance/guidance/manuals/downloads/clm104c25.pdf
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Last Updated: 2026-05-29
Sources: CMS Pub. 100-04 Chapter 25, NUBC Official UB-04 Manual, Medicare Contractor Bulletins (Noridian, Palmetto, CGS)