UB04 Admission Hour Code 13: 01:00 PM - 01:59 PM

Overview

The UB-04 admission hour code 13 corresponds to the hour block 01:00 PM – 01:59 PM (1:00 PM to 1:59 PM). This code is part of the military‑time (00–23) notation used in Field 13 – Admission/Start of Care Date on inpatient bills. According to CMS transmittal R1915CP, “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]. Therefore, code 13 uniquely identifies admission occurring between 1:00 PM and 1:59 PM. The same field also captures the calendar date of admission; the hour code is appended to that date to provide precise time‑of‑day documentation. MassHealth’s UB-04 billing guide confirms that providers must follow standard UB-04 code sets, including admission hour codes under “Code Sets for the UB-04 Claim Form” ^[2].

When to Use

Use code 13 when the patient’s admission (inpatient) or start of care (outpatient) falls within the 1:00 PM to 1:59 PM timeframe. Per CMS instructions, “FL 13 — Admission/Start of Care Date… Required on inpatient bills only. Enter the date the patient was admitted for inpatient care or the date outpatient care began” ^[1]. For example, if a patient is physically admitted to the inpatient unit at 1:25 PM, the billing staff enters code 13 in the admission hour field. The code is also appropriate for outpatient observation or emergency department visits that convert to inpatient status during that hour; the hour recorded should reflect the actual start of inpatient care. MassHealth requires electronic claims submission for most providers, but the admission hour code applies equally to paper and electronic formats ^[2].

Step-by-Step Claim Example

A patient arrives at the hospital emergency department at 12:45 PM on March 15, 2025. She is admitted to an inpatient bed at 1:17 PM the same day.

1. Field 12 – Patient Control Number: Internal account number (e.g., PAT12345).
2. Field 13 – Admission/Start of Care Date: Enter the calendar date 03‑15‑2025 (MM‑DD‑CCYY).
3. Field 13 – Admission Hour: Append the two‑digit military hour code 13. The combined value in Field 13 might appear as 03-15-2025 13 or in separate sub‑fields depending on the billing format. For the paper UB-04, the date and hour are typically written as a single line, e.g., 0315202513.
4. Field 14 – Priority (Type) of Admission: Choose appropriate code (e.g., 1 for emergency).
5. Field 15 – Source of Admission: Select the source (e.g., 7 for emergency room).

The CMS transmittal emphasizes that “the admission hour code (00–23) represents the hour of admission in military time” ^[1]. Therefore, 13 is correct because 1:17 PM falls between 1:00 PM and 1:59 PM. After completing all required fields, the claim is submitted electronically (per MassHealth policy) ^[2]. The payor will use the time code to validate length‑of‑stay and admission patterns.

Common Mistakes & Audit Red Flags

• Using code 13 for 1:00 AM: Code 13 is 1:00 PM; 1:00 AM is code 01. This is a frequent error that can cause payment delays or denials.
• Entering the wrong date: The admission hour must pair with the correct admission date. If the admission happened on March 16 at 1:10 AM, code 01 (not 13) should be used.
• Omitting the hour code entirely: Some billers leave the hour field blank or enter “00” when unsure.
• Mis‑reading military time: 13:00 is 1:00 PM, not 1:00 AM. Auditors often cross‑check recorded times with clinical documentation (e.g., nursing notes, physician orders).
• Using code 13 for outpatient only claims: While FL 13 is required on inpatient bills, it is optional for outpatient. However, if reported, the hour must match actual start of care.
• Inconsistent time zones: All times should be documented in the facility’s local time. MassHealth does not specify a different time zone rule, so standard local time applies ^[2].
• Rounding errors: If the admission occurred at 1:59 PM, code 13 is still correct; there is no separate “13:59” code. The hour block covers the full 60‑minute span.

Related Codes/Fields

The table below lists admission hour codes that are commonly used alongside code 13, as well as the related UB-04 field.

Field/Code	Description	Source
Field 13 – Admission Hour	Military‑time hour (00–23) appended to admission date	[1]
Code 00	12:00 AM – 12:59 AM (midnight hour)	[1]
Code 01	1:00 AM – 1:59 AM	[1]
Code 12	12:00 PM – 12:59 PM (noon)	[1]
Code 13	1:00 PM – 1:59 PM	[1]
Code 23	11:00 PM – 11:59 PM	[1]
Code 99	Unknown / not specified admission hour	[1]
Field 14 – Admission Type	Priority code (e.g., 1=emergency, 2=urgent, 3=elective)	[2]
Field 15 – Admission Source	Origin of patient (e.g., 7=emergency room, 9=physician referral)	[2]

Note: All codes shown above are part of the standard UB-04 code set referenced in the CMS transmittal and the MassHealth billing guide ^[1]; ^[2].

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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