UB04 Field 5: Federal Tax Number

Overview

The Federal Tax Number, located in Form Locator (FL) 5 of the UB-04 claim form, is the unique identification number assigned to a healthcare provider by the federal government for tax reporting purposes ^[1]. This field is a mandatory requirement for both inpatient and outpatient billing submissions to ensure proper identification of the entity responsible for the services rendered ^[2]. For Critical Access Hospitals (085X), this field is explicitly listed as a required element for successful claim processing ^[2]. The data entered here allows payers to link the claim to the provider's financial records for tax documentation and reporting ^[1].

The standardized format for the Federal Tax Number is a 10-position string following the pattern NN-NNNNNNN ^[1]. While electronic submissions may vary based on specific clearinghouse requirements, paper claims must include the hyphen to be considered valid ^[1]. Although some specific state programs, such as Maryland Medicaid, may designate this field as "Not required" for their specific processing systems, federal guidelines and Medicare standards maintain it as a required field for standard UB-04 submissions ^[1].

When to Use

The Federal Tax Number must be used on every UB-04 claim form submitted by institutional providers, including Critical Access Hospitals ^[2]. It is used whenever a provider needs to report services to the federal government or insurance carriers for reimbursement and tax reporting ^[1]. This field is essential for both inpatient and outpatient services to ensure the billing entity is correctly identified within the payer's system ^[2].

While the field is universally required by CMS, providers should note that specific state Medicaid programs may have different internal requirements regarding whether they utilize this specific box for their own adjudication ^[1]. However, to maintain compliance with standard UB-04 billing instructions and to avoid potential rejections from federal payers, the number should be populated according to the NN-NNNNNNN format ^[1].

Step-by-Step Claim Example

To complete FL 5 on a UB-04 claim form, follow these specific formatting and data entry steps:

1. Identify the Provider's Tax ID: Locate the nine-digit number assigned to the facility or provider by the federal government for tax reporting ^[1].
2. Format for Paper Claims: If submitting a physical paper claim, prepare the number in a 10-position format that includes the hyphen ^[1]. For example, if the tax ID is 123456789, it must be written as 12-3456789 ^[1].
3. Enter Data in Box 5: Place the formatted number into the field labeled "Federal Tax Number" (FL 5) ^[1].
4. Verify Against Statement Period: Ensure the tax number corresponds to the entity providing services during the "Statement Covers Period" (FL 6) ^[2].
5. Check for Consistency: Confirm that the Federal Tax Number matches the provider information associated with the facility's billing profile to prevent identification errors ^[1].
6. Review for Critical Access Hospitals: If billing as a Critical Access Hospital (085X), double-check that this field is populated, as it is a mandatory requirement for these specific providers ^[2].

Common Mistakes & Audit Red Flags

One of the most frequent errors in FL 5 is the omission of the hyphen on paper claim submissions ^[1]. The standard format requires 10 positions, including the hyphen (NN-NNNNNNN); failing to include this character can lead to automated system rejections or manual processing delays ^[1]. Another common mistake is the use of an incorrect tax ID that does not match the provider's registered information on file with the payer, which can trigger an audit or claim denial ^[1].

Additionally, providers must be careful not to confuse the Federal Tax Number with other identification numbers, such as NPI or state-specific Medicaid IDs ^[1]. While Maryland Medicaid notes the field as "Not required" for their specific processing, ignoring this field on claims sent to Medicare or other federal contractors will result in a failure to meet mandatory "Required" status for those payers ^[1].

Related Codes/Fields

Field	Name	Description
FL 4	Type of Bill	A four-digit code (e.g., 085X for Critical Access Hospitals) that indicates the type of facility and care [2].
FL 6	Statement Covers Period	The beginning and ending dates (MMDDYY) for the services covered on the claim [1].
FL 6 (From)	From Date	The earliest date of service on the bill [1].
FL 6 (Through)	Through Date	The date through which the payer is covering accommodations; it should not be the date of discharge for Medicaid [1].

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References

[1] Maryland Medicaid — FL 5 — https://health.maryland.gov/mmcp/provider/Documents/ffs-billing/UB04-Hospital-Billing-Instructions%20%281%29.pdf

[2] CMS R1915CP — UB-04 Requirements — FL 5 — https://www.cms.gov/regulations-and-guidance/guidance/manuals/downloads/clm104c25.pdf