UB04 Field 29: Accident State

Overview

Field 29 (Accident State) on the UB-04 claim form captures the two‑digit postal abbreviation of the state, province, or sub‑country where an auto accident occurred, when the services billed are related to that accident. The field is designated as situational by some payers, meaning it should be completed only when the accident location has a state or province code and the claim is for automobile‑related injuries. However, official guidance from the Centers for Medicare & Medicaid Services (CMS) explicitly states that FL 29 is not used and any data entered will be ignored. ^[1] In contrast, the Maryland Medicaid program treats the field as situational, requiring the two‑digit state abbreviation when the services reported are related to an auto accident and the accident occurred in a location that has a state, province, or sub‑country code. ^[2] This contradiction creates a split between federal Medicare processing (which ignores the field) and certain state Medicaid or commercial payer requirements that still rely on the data for auto‑accident liability determination. Providers must verify each payer’s specific instructions before populating the field.

When to Use

The decision to populate Field 29 depends entirely on the payer’s billing instructions. For Medicare fee‑for‑service claims, the field is explicitly marked as not used; any entry will be bypassed by the processing system. ^[1] Therefore, providers submitting to Medicare should leave the field blank or enter “XX” only if required by software validation – but note that the data will have no effect.

For state Medicaid programs (e.g., Maryland) and many commercial insurers that follow the NUBC (National Uniform Billing Committee) definition, Field 29 is situational. It must be completed when:

• The billable services are directly related to an automobile accident.
• The accident occurred in a location that has a state, province, or sub‑country code (e.g., “CA” for California, “ON” for Ontario, Canada).

If the accident did not occur in a state/province (e.g., on the high seas), or if the services are not accident‑related, the field should be left blank. ^[2] Note that the field is not intended for work‑related injuries or slip‑and‑fall incidents – only auto accidents with a definable state/province location.

Step-by-Step Claim Example

Assume a patient is injured in an auto accident that occurred in Chicago, Illinois (state abbreviation “IL”). The hospital is billing for inpatient services related to that accident. The payer is the Illinois state Medicaid program (which follows NUBC instructions).

Step 1: Confirm accident relation. The medical record must clearly document that the injuries were sustained in a motor vehicle accident. This is often supported by an occurrence code (e.g., code 45 for auto accident) in Fields 31–34.

Step 2: Determine the accident location. Obtain the exact address where the accident happened. For this example, the accident occurred in Cook County, Illinois – a state with a recognized two‑digit abbreviation “IL”.

Step 3: Locate Field 29 on the UB-04. Box 29 is typically found on the second line of the header section, between Patient Control Number and Medical/Health Record Number.

Step 4: Enter the two‑digit state abbreviation. Type “IL” (without quotes) left‑justified. Do not enter the full state name, punctuation, or a leading zero. ^[2]

Step 5: Verify payer requirements. If the same claim were sent to Medicare, Field 29 would be ignored, but many clearinghouses still require a value to pass edit checks. A common workaround is to enter “XX” when the field is not required but must be completed to avoid rejection – however, this should only be done if the payer’s instructions explicitly allow it.

Result: The claim shows FL 29 = “IL”, indicating the auto accident state, which may trigger coordination with the auto insurance carrier or a liability recovery process.

Common Mistakes & Audit Red Flags

• Using a full state name instead of the two‑digit code. Enter “Massachusetts” instead of “MA”. Payers expect only the abbreviation. ^[2]
• Including a value for a non‑auto accident. Some facilities populate FL 29 with “00” or “XX” for all trauma claims, but the field should only be used when the services are auto accident‑related. Unnecessary data can confuse recovery systems.
• Using a state that does not correspond to a real accident location. Entering “NY” when the accident occurred in Pennsylvania flags the claim for manual review and potential denial.
• Ignoring Medicare’s “not used” rule. Submitting FL 29 to Medicare with a real state code will not cause a denial, but it also will not be processed – meaning the payer may not initiate liability coordination. Auditors look for fields that contradict known payer rules.
• Forgetting to pair with an Occurrence Code. Many payers expect that if FL 29 is populated, Fields 31‑34 should contain an occurrence code indicating the accident (e.g., code 45). Missing the occurrence code can cause a claims edit failure.
• Leaving the field blank when a payer requires it. Certain state Medicaid programs may reject a claim if FL 29 is missing for an accident‑related service. Always verify the payer’s manual.

Related Codes/Fields

The table below lists fields and codes that often interact with or provide context for Field 29 on the UB-04 claim.

Field / Code	Description	Relationship to FL 29
FL 30 (Untitled)	Not used by CMS; data ignored. Reserved by NUBC.	No direct relationship; some payers may repurpose, but FL 29 is separate. [1]
FL 31–34 (Occurrence Codes & Dates)	Codes defining significant events (e.g., auto accident = code 45).	Required when FL 29 is used; the occurrence code justifies the accident state. [2]
FL 10 (Patient Name)	Patient identifier.	Not directly related, but insured name may be used to cross‑check accident report.
FL 55–56 (Principal Diagnosis & Admitting Diagnosis)	ICD‑10 codes for injury (e.g., V codes for car occupant accident).	Supports medical necessity for accident‑related treatment.
Condition Codes (FL 18–28)	Many condition codes (e.g., 77 – auto accident) can indicate accident type.	Condition code may duplicate or supplement the accident state information.
Payer-specific codes	Some Blue Cross or commercial plans request a specific accident state code.	Always check the payer’s provider manual for any additional requirements beyond NUBC definition.

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References

[1] CMS Chapter 25 — FL 29 — https://www.cms.gov/regulations-and-guidance/guidance/manuals/downloads/clm104c25.pdf

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