UB04 Reference

UB04 Field 11: Patient Sex

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UB04 Fields / field-11

Overview

Field 11 (Patient Sex) is a required data element on the UB-04 (CMS-1450) claim form used to identify the biological sex or administrative gender of the patient at the time of admission or start of care. This field is located in the top-right quadrant of the claim form, immediately following the patient's date of birth. It consists of a single-character alpha code that must align with the patient's records held by the primary payer.

The National Uniform Billing Committee (NUBC) and the Centers for Medicare & Medicaid Services (CMS) mandate this field for all institutional claims, including inpatient, outpatient, and home health services CMS Pub. 100-04 Chapter 25. While the field captures demographic data, its primary function in the revenue cycle is to trigger or bypass gender-specific clinical edits within the payer's adjudication system.

When to Use This Field

Field 11 is mandatory for every claim submission. The value entered must match the gender currently on file with the Social Security Administration (for Medicare) or the state Medicaid agency.

Scenario 1: Standard Gender-Specific Procedures

When billing for services that are biologically specific—such as a prostatectomy or a hysterectomy—the value in Field 11 must correspond to the procedure to avoid immediate rejection. For example, a claim for a screening mammography (CPT 77067) typically requires an "F" in Field 11 to pass initial automated edits Medicare Claims Processing Manual Chapter 25.

Scenario 2: Transgender and Gender-Incongruent Care

In cases where a patient's experienced gender or the service provided does not match the sex on their insurance record, Field 11 must still reflect the sex registered with the payer. To prevent denials for "gender/procedure mismatch," billers must use Condition Code 45 (Gender Incongruence) in Fields 18–28. This alerts the payer that the conflict is intentional and medically necessary CMS MLN Matters MM13101.

Step-by-Step Claim Example

Patient Scenario: A 45-year-old transgender male (assigned female at birth) is admitted to an acute care hospital for a medically necessary total abdominal hysterectomy due to symptomatic fibroids. The patient's Medicare record still lists the sex as "Female."

  1. Field 8b (Patient Name): Enter the patient's legal name as it appears on the Medicare card.
  2. Field 10 (Birthdate): Enter the patient's date of birth (MMDDYYYY).
  3. Field 11 (Sex): Enter F. Even if the patient identifies as male, the claim will reject if this does not match the "Female" designation on the Medicare eligibility file.
  4. Field 18-28 (Condition Codes): Enter 45. This code (revised July 1, 2023, to "Gender Incongruence") instructs the payer to bypass the edit that would normally deny a hysterectomy for a patient who might otherwise be identified as male in clinical notes NUBC Official UB-04 Data Specifications.
  5. Field 44 (HCPCS/CPT): Enter the appropriate surgical code (e.g., 58150).
  6. Payer Response: The claim passes the "Sex/Procedure" edit due to the presence of Condition Code 45 and is processed for payment rather than receiving a CARC 7 (The procedure/revenue code is inconsistent with the patient's gender) X12 CARC List.

Common Mistakes & Audit Red Flags

  • Eligibility Mismatch: Entering a gender based on the patient's current identity rather than their insurance record. This results in a CARC 177 (Patient has not met the required eligibility requirements) or a front-end rejection before the claim reaches an examiner AAPC Billing Forum.
  • Missing Condition Code 45: Failing to append Condition Code 45 when a gender-specific service is performed on a patient with a discordant sex marker in Field 11. This is a leading cause of "Inconsistent Gender" denials.
  • Typographical Errors: Entering "M" for "F" or leaving the field blank. As a "Required" field, any omission will cause the claim to be Returned to Provider (RTP).

Related Codes & Fields

Child Codes

References

  1. CMS Pub. 100-04 Chapter 25
  2. Medicare Claims Processing Manual Chapter 25
  3. CMS MLN Matters MM13101
  4. NUBC Official UB-04 Data Specifications
  5. X12 CARC List
  6. AAPC Billing Forum

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FormJuicer Data Insights

This guide was developed by the FormJuicer Billing Research Team using official CMS and NUBC guidelines, combined with patterns observed from processing thousands of real UB-04 documents through our system.

Last Updated: 2026-05-01

Sources: CMS Pub. 100-04 Chapter 25, NUBC Official UB-04 Manual, Medicare Contractor Bulletins (Noridian, Palmetto, CGS)