UB04 Field 5: Federal Tax Number

Overview

UB-04 Field 5, labeled as Federal Tax Number, is a mandatory field used to identify the billing facility’s tax identity for IRS reporting and claim adjudication. This field sits in the top-left quadrant of the CMS-1450 (UB-04) form, immediately to the right of the Statement Covers Period (Field 6) and below the Billing Provider Name and Address (Field 1). It captures the facility's nine-digit Employer Identification Number (EIN) or Tax Identification Number (TIN) assigned by the Federal Government CMS Pub. 100-04 Chapter 25.

Payers use this number to link the claim to the provider's 1099 tax records and to verify that the billing entity matches the contract on file. In the electronic 837I institutional claim format, this data maps to the Loop 2010AA, REF segment with an "EI" qualifier X12.org Standards. While the National Provider Identifier (NPI) in Field 56 identifies the clinical entity, Field 5 identifies the legal financial entity responsible for the debt and taxes.

When to Use This Field

This field is required for every institutional claim submission, regardless of whether the services are inpatient or outpatient. It is a "hard-coded" requirement for Medicare, Medicaid, and all commercial payers AmeriHealth UB-04 Requirements.

Real-World Billing Scenarios:

1. Multi-Facility Health Systems: A large hospital system may have five different campuses, each with a unique NPI (Field 56), but all campuses may roll up to a single corporate Federal Tax Number in Field 5. If a biller uses the campus-specific tax ID instead of the corporate ID registered with the payer, the claim will trigger a "Provider Not Found" or "Tax ID Mismatch" denial.
2. Change of Ownership (CHOW): When a Skilled Nursing Facility (SNF) is sold, the new owner must obtain a new EIN. During the transition period, claims must be split. Services rendered before the sale date must use the old Tax ID, while services after the sale must use the new Tax ID. Using the new Tax ID for dates of service prior to its effective date results in immediate rejection CMS Claims Processing Manual.

Step-by-Step Claim Example

Patient Scenario: A patient is admitted to an Acute Care Hospital for a three-day stay (Type of Bill 0111). The hospital's legal name is "City General," and its registered EIN is 12-3456789.

1. Field 1: Enter "City General Hospital" and the physical address.
2. Field 5: Enter the nine-digit tax number in the format NN-NNNNNNN. For this facility, enter 12-3456789.
3. Field 56: Enter the facility's NPI (e.g., 1234567890).
4. Submission: The claim is transmitted via the 837I electronic gateway.
5. Payer Response: The payer's front-end scrubber compares the EIN in Field 5 and the NPI in Field 56 against their provider master file. If the EIN 12-3456789 is linked to NPI 1234567890 in the payer's system, the claim passes to the adjudication engine. If the biller accidentally entered 12-3456780, the payer issues a CO-16 denial (Claim/service lacks information or has a submission/billing error) with remark code N290 (Missing/incomplete/invalid billing provider tax identification number).

Common Mistakes & Audit Red Flags

• Format Errors: Entering the number with spaces or without the hyphen on paper claims can cause Optical Character Recognition (OCR) errors. Medicare specifically requires the NN-NNNNNNN format CMS Pub. 100-04 Chapter 25.
• SSN vs. EIN: Small, unincorporated clinics or independent laboratories sometimes mistakenly enter the owner's Social Security Number (SSN) instead of a business EIN. Most institutional payers require a formal EIN for facility-based reimbursement.
• Mismatch with Field 56: The most frequent audit red flag is a mismatch between the Federal Tax Number and the Billing Provider NPI. Payers maintain a 1:1 or 1:Many relationship between these numbers. If a facility updates its tax ID with the IRS but fails to update its enrollment with the MAC or commercial payer, 100% of claims will be rejected Palmetto GBA Billing Instructions.

Related Codes & Fields

• Field 1: Billing Provider Name & Address
• Field 4: Type of Bill
• Field 56: National Provider Identifier (NPI)
• Field 57: Other Provider ID

References

1. CMS Pub. 100-04 Chapter 25
2. X12.org Standards
3. AmeriHealth UB-04 Requirements
4. CMS Claims Processing Manual
5. Palmetto GBA Billing Instructions