UB04 Admission Hour Code 20: 08:00 PM - 08:59 PM

Overview

Admission Hour Code 20 represents the one-hour window from 08:00 PM to 08:59 PM on the UB-04 claim form. This code is entered in Field 13 (Admission/Start of Care Date) and must be reported in military time (00–23). According to the CMS transmittal, “The admission hour code (00-23) represents the hour of admission in military time. Code 00 = 12:00 AM (midnight), 01 = 1:00 AM … 23 = 11:00 PM.” ^[1] Field 13 is “Required on inpatient bills only” and is used to record “the date the patient was admitted for inpatient care or the date outpatient care began.” ^[1] Therefore, code 20 is the correct choice when the admission or start-of-care hour falls between 8:00 PM and 8:59 PM. The MassHealth UB-04 Billing Guide confirms that the UB-04 form uses standardized code sets, reinforcing the need to use the correct hour code. ^[2]

When to Use

Code 20 should be used whenever a patient’s inpatient admission or outpatient start of care occurs during the 8:00 PM hour (20:00 to 20:59 military time). This applies to all inpatient hospital admissions, as Field 13 is required on inpatient bills. ^[1] For outpatient services, the field is optional but, if completed, must also use the same hour code set. The hour is always reported as a two-digit number from 00 to 23, with code 20 specifically covering the 8:00 PM–8:59 PM interval. ^[1] Providers should verify the exact time of admission or start of care from the medical record and convert it to military time. For example, an admission at 8:30 PM would be coded as 20. Using any other code for this time period (e.g., 08 for 8:00 AM) would be incorrect and could lead to claim rejection. The MassHealth guide emphasizes that all code sets on the UB-04 must be completed accurately to ensure proper processing. ^[2]

Step-by-Step Claim Example

Consider a patient admitted to the hospital on October 15, 2024, at 8:30 PM. The claim must be completed as follows:

1. Field 13 – Admission/Start of Care Date: Enter the date in the standard format (e.g., 10/15/2024). ^[1]
2. Hour Code: Immediately after or in the designated hour field, enter 20 (the two-digit military code for 8:00 PM–8:59 PM). ^[1]
3. Verification: Confirm that the time recorded in the patient’s medical record matches 20:30 (8:30 PM). No other hour code is acceptable for this time window.
4. Submission: The completed Field 13 will read “10/15/2024 20” (or the equivalent on the electronic claim). The MassHealth UB-04 Billing Guide notes that all paper UB-04 claims must follow the official code sets, and this example complies with the CMS definition. ^[2]

This example illustrates the correct application of code 20 for an inpatient admission. The same logic applies to outpatient start-of-care dates when the field is used.

Common Mistakes & Audit Red Flags

Several errors commonly occur with Admission Hour Code 20:

• Using 12-hour format: Reporting “8 PM” instead of the military code 20. CMS requires codes 00–23 only. ^[1]
• Confusing AM and PM: Code 08 represents 8:00 AM–8:59 AM, not 8:00 PM. Using 08 for an evening admission is a frequent mistake.
• Omitting the hour code: Field 13 requires both the date and the hour code on inpatient bills. Leaving the hour blank may cause the claim to be rejected. ^[1]
• Using code 24 or 00 for midnight: Midnight is code 00; there is no code 24. Code 20 should never be used for midnight.
• Inconsistent documentation: If the medical record shows 8:30 PM but the claim uses code 19 (7:00 PM–7:59 PM) or 21 (9:00 PM–9:59 PM), auditors may flag a discrepancy. Accurate conversion to military time is essential.

The MassHealth UB-04 Billing Guide stresses that providers must adhere to the official code sets to avoid payment delays. ^[2] Claims with incorrect hour codes may be returned or subjected to medical review.

Related Codes/Fields

The table below lists common admission hour codes and the related field on the UB-04.

Code	Meaning (Military Time)	Source
00	12:00 AM – 12:59 AM	[1]
08	08:00 AM – 08:59 AM	[1]
12	12:00 PM – 12:59 PM	[1]
20	08:00 PM – 08:59 PM	[1]
23	11:00 PM – 11:59 PM	[1]

Related Field: FL13 – Admission/Start of Care Date is the field where the date and hour code are entered. This field is required on inpatient bills and may be used for outpatient start-of-care dates. ^[1] The hour code is an integral part of this field. No other UB-04 field uses the admission hour code.

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References

[1] CMS R1915CP — https://www.cms.gov/Regulations-and-Guidance/Guidance/Transmittals/downloads/R1915CP.pdf

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