UB04 Field 30: Future Use

Overview

Field 30 (Box 30) on the UB-04 claim form is designated as "Reserved for Assignment by NUBC" and is not used for billing purposes. According to CMS Chapter 25, "FL 30 - (Untitled) Not used. Data entered will be ignored" ^[1]. This means any data submitted in this field will be disregarded by Medicare and other payers that follow CMS guidelines. The National Uniform Billing Committee (NUBC) has reserved this field for future assignment, and it should remain blank on all claims. Maryland Medicaid also confirms this: "FL 30 Reserved for Assignment by NUBC Not Used" ^[2]. Providers should never enter information in this field, as it serves no current billing function and may cause confusion or rejection if populated incorrectly.

When to Use

Field 30 should never be used under any circumstances. Both CMS and Maryland Medicaid explicitly state that this field is not used and data entered will be ignored ^{[1] [2]}. There are no situational requirements, conditional triggers, or payer-specific exceptions that would justify populating this field. It is reserved for future assignment by the NUBC, meaning it may eventually be assigned a specific purpose, but currently it remains unused. Providers should leave this field completely blank on all inpatient and outpatient UB-04 claims. Attempting to use this field for any data—whether for internal tracking, notes, or other purposes—will result in that data being ignored by payers and may lead to claim processing delays or rejections if the field is populated with invalid characters.

Step-by-Step Claim Example

Since Field 30 is never used, the step-by-step process is straightforward:

1. Review the UB-04 claim form and locate Box 30, which is typically positioned between Box 29 (Accident State) and Box 31 (Occurrence Codes).
2. Do not enter any data in Field 30. Leave it completely blank.
3. Verify that no other fields are inadvertently populated with data intended for Field 30. For example, if you have occurrence codes to report, they should go in Fields 31-34, not Field 30.
4. Proceed to complete Fields 31-34 for occurrence codes and dates, as these are situational fields that may require data ^[1].
5. Submit the claim with Field 30 blank. The payer will ignore any data entered in this field, but leaving it blank ensures compliance with NUBC standards and avoids potential issues.

Example: A hospital submits a UB-04 for an inpatient stay. The claim includes occurrence code 42 (Date of Death/Discharge) in Field 31, but Field 30 remains blank. The claim processes successfully because Field 30 is correctly left unused.

Common Mistakes & Audit Red Flags

Common mistakes with Field 30 include:

• Entering data in Field 30 thinking it is a required field or a place for notes. This is incorrect and will result in ignored data ^[1].
• Confusing Field 30 with Field 29 (Accident State) or Fields 31-34 (Occurrence Codes). Providers may accidentally place accident state information or occurrence codes in Field 30, which will be ignored and may cause downstream processing errors.
• Using Field 30 for internal tracking or reference numbers. This is not permitted and may lead to claim rejection if the field is populated with non-standard characters.

Audit red flags include:

• Claims with data in Field 30 may be flagged for review, as payers may question why a reserved field is populated.
• Inconsistent use across multiple claims from the same provider could indicate a systemic billing error.
• Rejected claims due to invalid data in Field 30, though rare, can occur if the field is populated with characters that trigger edits.

To avoid these issues, always leave Field 30 blank and train billing staff to recognize it as a reserved, unused field.

Related Codes/Fields

Field/Code	Description	Source
FL 29	Accident State – Report two-digit state abbreviation for auto accident-related services	[2]
FL 31-34	Occurrence Codes and Dates – Report codes and dates for significant events affecting payer processing	[1]
FL 35-36	Occurrence Span Codes – Report start and end dates for events spanning multiple days	[2]
FL 81	Code-Continuation – Overflow field for additional occurrence codes when FL 31-34 are exhausted	[2]
Condition Codes	Used for abortion (AA-AH), sterilization, and hysterectomy reporting on UB-04 claims	[2]

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References

[1] CMS Chapter 25 — FL 30 — https://www.cms.gov/regulations-and-guidance/guidance/manuals/downloads/clm104c25.pdf

[2] Maryland Medicaid — FL 30 — https://health.maryland.gov/mmcp/provider/Documents/ffs-billing/UB04-Hospital-Billing-Instructions%20%281%29.pdf