UB04 Patient Sex Code F: Female

Overview

The UB-04 Patient Sex Code F, located in Form Locator 11 (FL11), indicates that the patient is female. This code is a single alphanumeric character that identifies the patient's sex for billing and claims processing purposes. According to the CMS Medicare Claims Processing Manual, FL11 is defined as "Patient Sex" with a field size of one alphanumeric character and a buffer space of two characters ^[1]. The National Uniform Billing Committee (NUBC) maintains the approved coding for this field, and Medicare Administrative Contractors (A/B MACs) responsible for processing institutional claims must be able to capture all NUBC-approved input data for audit trail purposes ^[1]. The MassHealth UB-04 Billing Guide confirms that the UB-04 claim form includes specific code sets for completing the form, and providers must follow these standardized codes when submitting claims ^[2]. This field is essential for accurate patient identification and ensures proper claims processing across multiple payers, including Medicare and MassHealth.

When to Use

Use code F in FL11 when the patient being billed for is biologically female. This code must be entered for all institutional claims submitted on the UB-04 form, including inpatient and outpatient services, as the CMS instructions state that "Instructions for completion are the same for inpatient and outpatient claims unless otherwise noted" ^[1]. The field is mandatory for all claims submitted to Medicare, MassHealth, and other third-party payers that require patient sex identification. Providers should verify the patient's sex from their medical records or patient intake forms before entering this code. The MassHealth Billing Guide emphasizes that all claims must be submitted electronically unless the provider has received an approved electronic claim submission waiver, and the same coding standards apply to electronic submissions ^[2]. This code is particularly important for coordination of benefits, as the A/B MAC must be able to pass coordination of benefits data to other payers with whom it has a coordination of benefits agreement ^[1].

Step-by-Step Claim Example

Scenario: A 45-year-old female patient, Jane Doe, is admitted to General Hospital for a cholecystectomy. The billing department prepares the UB-04 claim form.

Step 1: Locate Form Locator 11 on the UB-04 form. According to the CMS layout, FL11 is described as "Patient Sex" with a line type of 1, an alphanumeric field, size of 1 character, and a buffer space of 2 characters ^[1].

Step 2: Verify the patient's sex from the medical record. Jane Doe's admission paperwork indicates she is female.

Step 3: Enter the code "F" in the single-character field of FL11. Do not add any spaces, punctuation, or additional characters. The buffer space of two characters allows for proper formatting on the form.

Step 4: Complete the remaining required fields on the UB-04 form, including FL08 (Patient Name), FL10 (Patient Birthdate), and FL12 (Admission/Start of Care Date) ^[1].

Step 5: Submit the claim electronically to the appropriate payer. For MassHealth claims, the MassHealth Billing Guide states that all claims must be submitted electronically unless an approved waiver is obtained ^[2].

Common Mistakes & Audit Red Flags

Common Mistakes:

1. Using incorrect codes: Entering "M" for male when the patient is female, or leaving the field blank. The CMS manual specifies that FL11 must contain a single alphanumeric character ^[1].
2. Adding extra characters: Including spaces, hyphens, or other characters in the field. The field size is exactly one character with a buffer space of two ^[1].
3. Inconsistent data: Entering a sex code that conflicts with other patient demographic information, such as a diagnosis code that is inconsistent with the patient's sex.

Audit Red Flags:

1. Missing or invalid sex codes: Medicare Administrative Contractors may flag claims with missing or invalid FL11 entries for review, as the A/B MAC must be able to capture all NUBC-approved input data for audit trail purposes ^[1].
2. Pattern of errors: Repeated use of incorrect sex codes across multiple claims may trigger a billing audit or request for medical records.
3. Coordination of benefits issues: Incorrect sex codes can cause problems when passing coordination of benefits data to other payers, as the A/B MAC must be able to pass this data to payers with which it has a coordination of benefits agreement ^[1].

Related Codes/Fields

Field/Code	Description	Source
FL08	Patient Name and Identifier	[1]
FL10	Patient Birthdate	[1]
FL11	Patient Sex (Code F = Female)	[1]
FL12	Admission/Start of Care Date	[1]
FL03a	Patient Control Number	[1]
FL03b	Medical/Health Record Number	[1]
FL09	Patient Address	[1]
FL38	Responsible Party Name/Address	[1]

---

References

[1] CMS Chapter 25 — https://www.cms.gov/regulations-and-guidance/guidance/manuals/downloads/clm104c25.pdf

[2] MassHealth UB-04 Guide — https://www.mass.gov/doc/ub-04-billing-guide-0/download