UB04 Diagnosis/Procedure Code Qualifier Code 0: ICD-10-CM

Overview

Code 0 in Form Locator 66 (Diagnosis/Procedure Code Qualifier) on the UB-04 claim form indicates that the diagnosis codes reported on the claim are coded using ICD-10-CM (International Classification of Diseases, 10th Revision, Clinical Modification). This qualifier is maintained by the National Uniform Billing Committee (NUBC) and is used by Medicare and other payers to identify the coding system applied to the principal and secondary diagnosis codes entered in Form Locators 67 through 69. ^[1] (Section 75.6) specifies that Form Locator 66 must contain a valid NUBC-approved code to indicate the version of diagnosis coding used. The UB-04, also known as Form CMS-1450, is a uniform institutional provider bill suitable for billing multiple third party payers, and all items on the form are described in the Medicare Claims Processing Manual. ^[1] (Section 70.1) notes that because the form serves many payers, a particular payer may not need some data elements, but Medicare Administrative Contractors must capture all NUBC-approved input data for audit trail purposes. Code 0 specifically maps to ICD-10-CM, which became the mandated coding standard for all HIPAA-covered entities in the United States on October 1, 2015, replacing ICD-9-CM. ^[2] (Page 23) confirms that code sets for the UB-04 claim form, including diagnosis code qualifiers, are maintained by the NUBC and adopted by MassHealth for claims processing.

When to Use

Use code 0 in Form Locator 66 whenever the diagnosis codes reported on the UB-04 claim (Form Locators 67, 68, and 69) are coded using ICD-10-CM. This applies to all institutional claims submitted to Medicare, Medicaid (including MassHealth), and most commercial payers for services rendered on or after October 1, 2015. ^[1] (Section 75.6) requires that the qualifier code accurately reflect the coding system used for the diagnosis codes on the claim. For Medicare claims, the A/B MAC (A) or (HHH) must be able to capture all NUBC-approved input data, including the diagnosis code qualifier, for audit trail purposes and to pass coordination of benefits data to other payers. ^[1] (Section 70.1) states that Medicare Administrative Contractors servicing both Part A and Part B lines of business (A/B MACs (A) and (HHH)) responsible for receiving institutional claims maintain lists of codes used by Medicare. Code 0 should not be used for ICD-9-CM codes (which would use qualifier code 9) or for any other coding system. The qualifier must be entered as a single alphanumeric character in Form Locator 66, and it applies to all diagnosis codes listed on the claim. ^[2] (Page 4) provides instructions for completing the UB-04 claim form, including the requirement to use correct code sets for all data elements.

Step-by-Step Claim Example

Scenario: A hospital submits a UB-04 claim for an inpatient admission with a principal diagnosis of pneumonia (ICD-10-CM code J18.9) and a secondary diagnosis of hypertension (ICD-10-CM code I10).

Step 1: Complete Form Locator 66 (Diagnosis/Procedure Code Qualifier). Enter 0 to indicate that all diagnosis codes on the claim are ICD-10-CM codes. ^[1] (Section 75.6) specifies that Form Locator 66 contains the qualifier for the diagnosis codes.

Step 2: Enter the principal diagnosis code in Form Locator 67. For this example, enter J18.9 (Pneumonia, unspecified organism). ^[1] (Section 75.6) describes Form Locator 67 as the principal diagnosis code field.

Step 3: Enter the secondary diagnosis code in Form Locator 68. For this example, enter I10 (Essential (primary) hypertension). ^[1] (Section 75.6) describes Form Locator 68 as the other diagnosis code field.

Step 4: If additional diagnosis codes are needed, enter them in Form Locator 69 (other diagnosis codes). ^[1] (Section 75.6) describes Form Locator 69 as the admitting diagnosis code field.

Step 5: Verify that the qualifier code in Form Locator 66 matches the coding system used for all diagnosis codes. Since both J18.9 and I10 are ICD-10-CM codes, code 0 is correct. ^[2] (Page 23) confirms that code sets for the UB-04 claim form must be used correctly.

Step 6: Submit the claim to the appropriate payer (e.g., Medicare A/B MAC, MassHealth, or commercial insurer). ^[1] (Section 70.2) states that the provider submits the completed Form CMS-1450 to its A/B MAC (A) or (HHH), managed care plan, or other insurer.

Common Mistakes & Audit Red Flags

Mistake 1: Using code 0 for ICD-9-CM codes. This is a critical error because ICD-9-CM codes (e.g., 486 for pneumonia) require qualifier code 9. Using code 0 with ICD-9-CM codes will cause claim rejection or denial. ^[1] (Section 75.6) requires that the qualifier code accurately reflect the coding system used.

Mistake 2: Leaving Form Locator 66 blank. A blank qualifier field may cause the claim to be rejected or returned for correction. ^[1] (Section 75) states that all items on Form CMS-1450 are described and must be completed according to Medicare requirements.

Mistake 3: Using code 0 when the claim contains a mix of ICD-10-CM and other coding systems. The qualifier applies to all diagnosis codes on the claim. If any diagnosis code is not ICD-10-CM, code 0 is incorrect. ^[2] (Page 4) emphasizes using correct code sets for all data elements.

Audit Red Flag: Claims with code 0 in Form Locator 66 but diagnosis codes that appear to be from an older coding system (e.g., codes starting with E or V that are not valid ICD-10-CM codes) will trigger audit scrutiny. ^[1] (Section 70.1) notes that Medicare Administrative Contractors must capture all NUBC-approved input data for audit trail purposes.

Audit Red Flag: Inconsistent use of code 0 across multiple claims from the same provider may indicate a systemic billing error. ^[1] (Section 75) requires that instructions for completion are the same for inpatient and outpatient claims unless otherwise noted.

Related Codes/Fields

Code/Field	Description	Source
Code 9	ICD-9-CM (used for claims with ICD-9-CM diagnosis codes)	[1]
Form Locator 67	Principal Diagnosis Code (ICD-10-CM code)	[1]
Form Locator 68	Other Diagnosis Codes (secondary diagnoses)	[1]
Form Locator 69	Admitting Diagnosis Code	[1]
Form Locator 70	Patient Reason for Visit (outpatient only)	[1]
Form Locator 71	Procedure Code Qualifier (e.g., 0 for ICD-10-PCS)	[1]
Form Locator 72	Principal Procedure Code and Date	[1]
Form Locator 74	Other Procedure Codes and Dates	[1]
Type of Bill (FL04)	Identifies the type of facility and bill (e.g., 111 for inpatient)	[1]
Patient Discharge Status (FL17)	Indicates patient disposition after discharge	[1]

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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