UB04 Field 35-36: Occurrence Span Codes and Dates

Overview

Occurrence span codes and dates, reported in Boxes 35–36 of the UB-04 claim form, capture a range of dates (a “from/through” period) associated with a specific clinical or administrative event during a patient’s stay or outpatient treatment. Unlike single-occurrence codes (Boxes 31–34), span codes always require two dates: a start date and an end date. These codes are not required for either inpatient or outpatient claims, but they are used when a particular event spans multiple days and must be communicated to the payer. ^[1]

The most commonly reported span codes include:

• 70 – Qualifying stay dates for SNF use only (SNF 3-day hospital stay). Also used for nonutilization dates (PPS inlier free days) when the beneficiary has exhausted all regular/coinsurance days but the stay is still covered on the cost report.
• 71 – Prior stay dates (Part A only) for a hospital stay ending within 60 days of the current admission.
• 72 – First/last outpatient visit dates, used when the from/through dates in FL 6 do not represent the entire billing record.
• 74 – Non-covered level of care/leave of absence dates during an otherwise covered stay.
• 75 – SNF level of care dates when a SNF bed is not available during an inpatient hospital stay.
• 76 – Patient liability dates for non-covered care the provider may charge the beneficiary.
• 77 – Provider liability period (utilization charged) for non-covered care the provider is liable for.
• 80 – Prior same-SNF stay dates for payment ban purposes.
• 82 – Hospital at Home care dates provided during an inpatient stay.
• M0 – QIO/UR approved stay dates, used when code C3 is in FL 24–30.
• M2 – Inpatient Respite dates for hospice patients.

^[1]

The MassHealth UB-04 billing guide confirms that the UB-04 claim form includes occurrence span codes as part of the standard code sets, though it does not list the specific definitions. ^[2]

When to Use

Occurrence span codes and dates are used when a single code must represent a continuous period of days. For example, code 71 (Prior stay dates) is entered when a patient reports a hospital stay that ended within 60 days of the current admission. The provider enters the from/through dates of that prior stay in Boxes 35–36. This helps payers identify potential readmission patterns or transfer-of-benefit periods. ^[1]

Code 70 is specific to SNF claims (TOB 2x or 8x) and must be used to report the three-day qualifying hospital stay dates for Medicare Part A SNF coverage. It is also used for nonutilization dates when the beneficiary has exhausted all regular and coinsurance days. ^[1]

Outpatient providers use code 72 to report the actual first and last service dates when the dates in FL 6 (statement covers period) do not reflect the full billing record—for instance, when a single bill spans multiple visits but only the first and last visit dates are needed for coverage determination. ^[1]

Code 74 is used to show a leave of absence or a non-covered level of care period within an otherwise covered stay. This is common in long-term acute care or psychiatric units where a patient may be on therapeutic leave for several days. The provider enters the from/through dates of that absence. ^[1]

Code 82 (Hospital at Home care dates) was added for inpatient stays where part of the care is delivered at the patient’s home. The span dates indicate that the patient received hospital-level services at home on those specific days. ^[1]

Finally, code M0 is used when a QIO/UR approval has been obtained and code C3 (approved by QIO/UR) is present in FL 24–30. The provider enters the approved billing period from/through dates. ^[1]

Step-by-Step Claim Example

Scenario: A Medicare patient is admitted to Hospital A on March 5, 2025. During the admission interview, the patient states they were discharged from another hospital on February 15, 2025 – within 60 days of the current admission. The billing department must report this prior stay.

Step 1: In Box 35, enter the occurrence span code 71 (Prior stay dates).
Step 2: In Box 36a, enter the from date of the prior stay – February 10, 2025 (assuming the prior stay started on that date).
Step 3: In Box 36b, enter the through date of the prior stay – February 15, 2025.
Step 4: Verify that the from/through dates in Box 36 are in the format MM/DD/YY or CCYYMMDD as required by the payer. ^[1]

Outcome: The occurrence span code 71 with dates Feb 10–15, 2025, is reported in FL 35–36. The payer (Medicare) will use this information to determine whether the current admission is a readmission or a transfer and whether the DRG payment should be adjusted.

Alternative example using code 72 (outpatient): An outpatient clinic provides services to a patient over multiple visits from February 1 to March 15, 2025. The statement covers period in FL 6 is February 1 – March 15, but the actual first visit was January 25 (pre-admission testing) and the last visit was March 20. To correctly report the service span, the provider enters code 72 in Box 35, with from date 01/25/2025 and through date 03/20/2025 in Box 36. This ensures the payer knows the full range of outpatient visits. ^[1]

Common Mistakes & Audit Red Flags

1. Using a single-occurrence code instead of a span code. Occurrence codes (Boxes 31–34) should not be used for dates that cover a range. If a period is required, always use Boxes 35–36 with the appropriate span code. Misplacement can cause claim denials. ^[1]

2. Leaving dates blank when code M0 is used. Code M0 (QIO/UR approved stay dates) requires both from and through dates. If the dates are missing, the claim may be rejected because the approval period is unknown. ^[1]

3. Using code 70 on acute hospital claims. Code 70 is for SNF use only. Acute hospitals should never report code 70; doing so may trigger an audit for improper billing. For SNF claims, the three-day qualifying stay dates must be accurate. ^[1]

4. Failing to report code 72 when FL 6 dates are incorrect. If the statement covers period in FL 6 does not match the actual first and last service dates, outpatient providers must use code 72 to avoid payment discrepancies. Auditors often cross-check FL 6 and FL 35–36 for consistency. ^[1]

5. Using expired or reserved codes. Code MR is reserved for disaster-related occurrence span use only. Providers should not report it unless specifically instructed by a payer. Similarly, code 79 is set aside for payer use only; providers must not report it. ^[1]

Related Codes/Fields

Field / Box	Description	Source
FL 6	Statement Covers Period (From/Through service dates)	[1]
FL 24–30	Value Codes and Amounts (e.g., code C3 for QIO/UR approval)	[1]
FL 31–34	Occurrence Codes and Dates (single-date events)	[2] (implies field exists)
FL 35–36	Occurrence Span Codes and Dates (this article)	[1]
FL 37–41	Blanket, Condition, Treatment, or Other Codes	[2] (general structure)

Note: The MassHealth UB-04 billing guide provides a complete list of all fields in the “How to Complete the UB-04 Claim Form” section. Refer to that guide for the full field layout. ^[2]

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References

[1] Noridian Occurrence Span — https://med.noridianmedicare.com/web/jea/topics/claim-submission/occurrence-span-codes

[2] MassHealth UB-04 Guide — https://www.mass.gov/doc/ub-04-billing-guide-0/download