UB04 Field 31-34: Occurrence Codes and Dates

Overview

Fields 31 through 34 on the UB-04 claim form are designated for Occurrence Codes and Dates, which provide specific event-related information that affects claim processing and payment [FIELD: Occurrence Codes and Dates (Box 31-34)]. These fields are used to report significant dates, such as the date of an accident, the onset of symptoms, or the start of specific therapy plans ^[1]. Each entry consists of a two-digit alphanumeric code followed by the date the event occurred [OCCURRENCE CODES]. These codes are essential for identifying third-party liability (TPL), such as auto accidents or employment-related injuries, which may determine which payer is primary [OCCURRENCE CODES]. For example, code 01 indicates an accident where medical payment coverage is available, while code 04 signifies an employment-related accident [OCCURRENCE CODES]. Additionally, these fields capture administrative milestones, such as the date a beneficiary was notified of an intent to bill for non-covered procedures (Code 32) or the date insurance benefits were terminated by a primary payer (Code 25) [OCCURRENCE CODES]. For MassHealth claims, these fields must be completed if applicable to the specific service or patient circumstance being billed [FIELD: Occurrence Codes and Dates (Box 31-34)].

When to Use

Occurrence Codes and Dates are required for both inpatient and outpatient claims when specific circumstances defined by the code set apply to the encounter [FIELD: Occurrence Codes and Dates (Box 31-34)]. In outpatient settings, providers must use code 11 to indicate the date of onset for symptoms or illness [OCCURRENCE CODES]. If a claim involves an accident, providers must select the appropriate code from 01 through 05 to describe the nature of the accident and the type of insurance coverage involved, such as No-Fault (Code 02) or Tort Liability (Code 03) [OCCURRENCE CODES].

Specialized facilities have unique requirements: Skilled Nursing Facilities (SNF) use code 26 to indicate when a bed became available, while Hospice providers use code 27 for certification dates or code 42 for discharges due to patient revocation [OCCURRENCE CODES]. For therapy services, codes 17, 28, 29, or 30 are used to report when a plan of care was established or last reviewed for occupational, physical, or speech therapy [OCCURRENCE CODES]. Furthermore, these fields are used to coordinate benefits, such as reporting the date a patient became eligible for Medicaid due to a medically needy spend-down (Code A4) or the birthdate of the insured (Codes A1, B1, or C1) [OCCURRENCE CODES].

Step-by-Step Claim Example

To complete Fields 31-34 for a patient who was injured in an auto accident and is now receiving outpatient physical therapy, follow these steps:

1. Identify the Primary Event: Determine if the injury is accident-related. If the state has no-fault laws and it was an auto accident, select Occurrence Code 02 [OCCURRENCE CODES].
2. Enter the Accident Date: In Field 31, enter "02" in the code portion and the date of the accident in the date portion [OCCURRENCE CODES].
3. Report Therapy Initiation: Since the patient is receiving physical therapy, identify the date treatment started. Use Occurrence Code 35 [OCCURRENCE CODES].
4. Enter Therapy Start Date: In Field 32, enter "35" followed by the date the physical therapy treatment actually commenced [OCCURRENCE CODES].
5. Report Plan Review: If the physical therapy plan was reviewed recently, use Occurrence Code 29 [OCCURRENCE CODES].
6. Enter Plan Date: In Field 33, enter "29" and the date the outpatient physical therapy plan was established or last reviewed [OCCURRENCE CODES].
7. Check for Other Coverage: If the patient's primary insurance benefits were exhausted, use code A3 for Payer A [OCCURRENCE CODES].
8. Enter Exhaustion Date: In Field 34, enter "A3" and the last date benefits were available from the primary payer [OCCURRENCE CODES].

Common Mistakes & Audit Red Flags

One common mistake is the improper use of outpatient-only codes on inpatient claims. For instance, Code 11 (Onset of Symptoms/Illness) and Code 40 (Scheduled Date of Admission) are explicitly restricted to outpatient claims only [OCCURRENCE CODES]. Using these on an inpatient UB-04 form may trigger a claim rejection or audit ^[2]. Another frequent error involves the misreporting of accident codes; choosing Code 01 (Medical Coverage) when Code 03 (Tort Liability) is more appropriate can lead to incorrect coordination of benefits and payment delays [OCCURRENCE CODES].

Additionally, for Hospice claims, failing to provide Code 27 (Date of Hospice Certification) or using the wrong code for discharge (Code 42 vs. Code 23) is a common compliance issue [OCCURRENCE CODES]. Finally, providers must ensure that if a "Date of Retirement" (Codes 18 or 19) is listed, it accurately reflects the status of the patient or spouse to justify secondary payer status [OCCURRENCE CODES].

Related Codes/Fields

Field	Description	Relationship to Occurrence Codes
Field 35-36	Occurrence Span Codes and Dates	Used for events that happen over a period of time rather than a single date [2].
Field 12-15	Admission Date/Hour	Must logically follow the "Onset of Symptoms" (Code 11) or "Accident Date" (Codes 01-05) [OCCURRENCE CODES].
Field 58	Insured's Name	Related to Codes A1, B1, and C1 which identify the birthdate of the insured [OCCURRENCE CODES].
Field 50	Payer Name	Related to Codes A3, B3, and C3 regarding the exhaustion of benefits for specific payers [OCCURRENCE CODES].
Field 31-34 (DR)	Disaster Related	Reserved for tracking services provided during a declared disaster [OCCURRENCE CODES].

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References

[1] OCCURRENCE CODES — https://med.noridianmedicare.com/web/jea/topics/claim-submission/occurrence-codes

[2] BG-UB-04 (02/21) — https://www.mass.gov/doc/ub-04-billing-guide-0/download