Overview
The UB-04 claim form (Form CMS-1450) is a uniform institutional provider bill used for billing multiple third-party payers, including Medicare [1]. The National Uniform Billing Committee (NUBC) maintains the lists of approved codes for the form [2]. Field 81CC (Code-Code Field/Qualifiers) is a situational field on the UB-04 [3]. Its purpose is to report additional codes related to a Form Locator or to report an external code list approved by the NUBC [3]. The field allows providers to supply qualifiers or supplementary coding information that supports data entered elsewhere on the claim [3]. Because the field is situational, it is not required for every claim; it is used only when the specific coding scenario demands additional qualifiers [3]. Medicare Administrative Contractors (A/B MACs) must be able to capture all NUBC-approved input data for audit trail purposes [1].
When to Use
Field 81CC is used when a claim requires additional codes or qualifiers that are directly related to another Form Locator on the UB-04 [3]. For example, if a diagnosis code entered in FL67 (Principal Diagnosis Code) originates from an external code list (e.g., a non-standard classification), the provider may use FL81 to report the qualifier identifying that external list [3]. The field is also appropriate when a Form Locator requires a code that is not part of the standard NUBC code set and must be supplemented by an approved external code list [3]. The field is situational, meaning it is not required for all claims; it is only completed when the coding circumstances warrant its use [3].
Step-by-Step Claim Example
Consider a hospital submitting a Medicare inpatient claim for a patient with a diagnosis that is coded using an external classification system approved by the NUBC. The provider enters the primary diagnosis code in FL67 (Principal Diagnosis Code) [1]. Because the code comes from an external code list, the provider must identify the source of that code. The qualifier in FL81 links directly to the diagnosis code in FL67, ensuring the payer understands the origin of the code [3]. The claim is then submitted electronically or on paper to the Medicare Administrative Contractor [1]. The A/B MAC processes the claim, capturing the FL81 data as part of the audit trail [1].
Common Mistakes & Audit Red Flags
One common mistake is using FL81 when the information could be reported in a standard Form Locator, leading to unnecessary complexity [3]. Providers sometimes enter incorrect qualifiers that do not match the approved NUBC external code lists, triggering audit flags [2]. Medicare expects that all NUBC-approved input data, including FL81, be captured for audit trail purposes; missing or inconsistent data may result in additional documentation requests [1]. To avoid red flags, providers should verify that the qualifier used in FL81 is listed in the current NUBC code set and that it directly corresponds to the related Form Locator [3]. Additionally, because the field is situational, using it when not needed can confuse payers and lead to unnecessary scrutiny [3].
Related Codes/Fields
The following table lists Form Locators that commonly interact with FL81 (Code-Code Field/Qualifiers). These fields may require qualifiers or supplementary codes that can be reported in FL81.
| Form Locator | Description | Relationship to FL81 |
|---|---|---|
| FL67 | Principal Diagnosis Code | FL81 may report the external code list qualifier for the diagnosis code entered here [3]. |
| FL72 | Occurrence Code | When an occurrence code originates from an external list, FL81 can provide the qualifier [3]. |
| FL80 | Remarks | FL81 can be used to supply a qualifier for remarks that reference an external code set [3]. |
| FL76 | Attending Provider | If a provider identifier comes from an external source, FL81 may indicate the source [3]. |
| FL39 | Value Codes | Value codes that require a qualifier from
References
[1] CMS Ch25 — https://www.cms.gov/regulations-and-guidance/guidance/manuals/downloads/clm104c25.pdf
[2] Find-A-Code — https://content.findacode.com/panelists/0/UB%2004_Claim_Form_Instructions.pdf
[3] CMS Manual System — https://ahca.myflorida.com/content/download/9611/file/ub04-manual.pdf
Need to extract UB04 data?
Upload your UB04 PDFs and get structured data in seconds.
Start ExtractingThis guide was developed using official CMS and NUBC guidelines, combined with patterns observed from processing thousands of real UB-04 documents through our system.
Last Updated: 2026-06-03
Sources: CMS Pub. 100-04 Chapter 25, NUBC Official UB-04 Manual, Medicare Contractor Bulletins (Noridian, Palmetto, CGS)