UB04 Admission Hour Code 04: 04:00 AM - 04:59 AM

The UB-04 Admission Hour Code 04 represents the hour interval from 04:00 AM through 04:59 AM, expressed in military (24-hour) time. ^[1] specifies that the admission hour code must be a two-digit value from 00 to 23, where 00 equals 12:00 AM (midnight), 01 equals 1:00 AM, and so on up to 23 for 11:00 PM. Code 04 therefore denotes that the patient was admitted between 04:00 AM and 04:59 AM on the date entered in Field 13.

^[2] notes that the paper claim form is still used by some providers, though Massachusetts has transitioned to an all-electronic submission policy effective January 1, 2012. Accurate reporting of the hour (including 04) ensures proper alignment with medical record documentation and supports claims adjudication.

When to Use

Use Admission Hour Code 04 exclusively when the patient’s admission or start of care occurred at any time between 04:00 AM and 04:59 AM on the date entered in Field 13. This applies to inpatient hospital admissions, skilled nursing facility admissions, and other institutional stays that require a precise admission time. The hour code must match the time documented in the patient’s medical record (e.g., physician order, nursing assessment, or registration timestamp). ^[2] reminds providers that all fields on the UB-04 must be completed accurately to avoid claim rejections; therefore, if the admission hour falls within the 04:00–04:59 window, code 04 must be used without rounding to the nearest hour. For example, an admission at 3:58 AM would use code 03, not 04, because code 03 covers 03:00–03:59.

Step-by-Step Claim Example

Consider a patient admitted to General Hospital on January 15, 2024, at 4:20 AM. The UB-04 claim is prepared as follows:

1. Field 12 – Patient Name and Address: Enter full patient name and address.
2. Field 13 – Admission/Start of Care Date: Enter 01/15/2024 (the date of admission). ^[1] requires this date to match the actual calendar day the inpatient stay began.
3. Field 13 – Admission Hour: Enter 04 (two digits). This indicates the admission occurred during the 04:00–04:59 hour. The hour must be military time; do not include minutes.
4. Field 14 – Type of Admission: Select the appropriate code (e.g., 1 for emergency, 2 for urgent, 3 for elective). Because the admission at 4:20 AM may be emergency or urgent, choose accordingly based on medical documentation.
5. Field 15 – Source of Admission: Enter the code (e.g., 1 for physician referral, 2 for clinic referral, 7 for emergency department). Document the source per CMS guidelines.
6. Other required fields: Complete all mandatory fields including Fields 1–11 (provider info, patient control number, etc.), Fields 42–44 (revenue codes and charges), and Fields 45–46 (service dates). For inpatient admissions, the statement covers period (Field 6) will reflect the full stay.

The claim is then submitted electronically or on paper. Using code 04 ensures the payer recognizes the early morning admission time. ^[2] stresses that all data elements must be consistent; for example, the admission hour should align with the time recorded in the medical record and the type of admission code (e.g., emergency admission at 4:20 AM is plausible).

Common Mistakes & Audit Red Flags

Several errors can trigger claim denials, payment delays, or audits when using Admission Hour Code 04:

• Incorrect hour range: Using code 04 for admissions that occur outside 04:00–04:59, especially rounding 5:00 AM down to 04. ^[1] defines each code as a fixed one-hour interval; rounding is not permitted. A 5:03 AM admission must be code 05.
• Missing or invalid code: Leaving Field 13 hour blank or entering a non-numeric value. Payers often reject claims with no admission hour for inpatient bills. Ensure two digits are always present.
• Mismatch with medical record: If the medical record shows admission at 04:10 but the claim shows code 05, auditors may flag this as a discrepancy. Maintain consistency between clinical documentation and billing. ^[2] warns that inaccuracies can lead to recoupments or penalties.
• Using code 04 for outpatient care: The admission hour field is required only on inpatient bills. Outpatient start-of-care dates do not require an hour code unless a specific payer mandates it. Submitting an hour code on an outpatient claim may cause errors.
• Typographical errors: Transposing digits (e.g., 40 instead of 04) is a common keying mistake. Code 40 does not exist in the 00–23 range and will be rejected. Double-check entry.
• Inconsistent date and time logic: If the admission hour is 04 but the admission date is later than the actual time (e.g., date is 01/15 but the patient was admitted after midnight on 01/14), correct the date to match. The hour and date must be congruent.

Providers should implement front-end edits to validate that the admission hour code falls within 00–23 and corresponds to the documented time. Regular audits of random claims can catch recurrent errors.

Related Codes/Fields (markdown table)

Field/Code	Description	Source
Field 13 (Date)	Admission/Start of Care Date – the calendar date of admission	[1]
Field 13 (Hour)	Admission Hour – two-digit code 00–23 representing the hour of admission	[1]
Code 00	12:00 AM – 12:59 AM (midnight hour)	[1]
Code 01	01:00 AM – 01:59 AM	[1]
Code 02	02:00 AM – 02:59 AM	[1]
Code 03	03:00 AM – 03:59 AM	[1]
Code 04	04:00 AM – 04:59 AM	[1]
Code 05	05:00 AM – 05:59 AM	[1]
Code 23	11:00 PM – 11:59 PM	[1]
Field 14	Type of Admission – code indicating emergency, urgent, elective, etc.	[2]
Field 15	Source of Admission – code for referral source	[2]
Field 6	Statement Covers Period – from–through dates for the entire stay	[2]

---

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