UB04 Admission Hour Code 16: 04:00 PM - 04:59 PM

Overview

Code 16 represents the admission hour of 04:00 PM to 04:59 PM in military time, corresponding to 16:00 hours on a 24-hour clock. This code is entered in Field 13 of the UB-04 claim form, which records the admission/start of care date and time for inpatient stays. According to the CMS transmittal, the admission hour code must use a two-digit format (00-23) to indicate the specific hour of admission, with Code 00 representing midnight (12:00 AM) and Code 23 representing 11:00 PM ^[1]. For Code 16, the admission occurred between 4:00 PM and 4:59 PM local time.

When to Use

Use Code 16 when the patient's inpatient admission occurred at any point during the 4:00 PM to 4:59 PM hour (16:00 to 16:59 in military time). This code applies exclusively to inpatient claims on the UB-04 form; it is not used for outpatient services, which typically record only the date of service. The admission hour code is critical for determining length of stay calculations, per diem reimbursement rates, and compliance with Medicare's midnight rule (which establishes the admission date based on the time of admission relative to midnight). For example, if a patient is admitted at 4:30 PM, Code 16 is the correct selection. This code is part of the required field for inpatient claims, per CMS instructions ^[1].

Step-by-Step Claim Example

Consider a patient admitted to the hospital at 4:15 PM on March 15, 2025. Step 1: In Field 13 of the UB-04 claim form, enter the admission date as "03-15-2025" (or "03152025" depending on payer format requirements). Step 2: Immediately to the right of the date field, enter the admission hour code "16" to indicate the admission occurred between 4:00 PM and 4:59 PM. Step 3: Verify that the total time documented in the medical record (e.g., 4:15 PM) corresponds to code 16. Step 4: For Medicare claims, confirm that the admission hour does not affect the admission date under the midnight rule (if admission is before midnight on day 1, the admission date is day 1; if at or after midnight, it is day 2). Step 5: Submit the claim as per payer guidelines. MassHealth requires electronic submission for all claims unless an exemption is approved, so ensure the code is transmitted in the appropriate electronic loop and segment ^[2]. This example illustrates the correct application of code 16 for timely billing.

Common Mistakes & Audit Red Flags

Common mistakes include using code 16 for outpatient services (where admission hour is not required) or entering a code that does not match the actual admission time. For instance, if a patient is admitted at 4:45 PM but the claim shows code 17 (5:00 PM to 5:59 PM), this discrepancy may trigger an audit by payers seeking to verify length of stay and reimbursement accuracy. Another frequent error is entering "16" in a format that is not two digits (e.g., "6" or "016")—code 16 must be exactly two digits. Auditors also flag claims where the admission hour code is missing or incomplete, as this field is mandatory for inpatient bills per CMS requirements ^[3]. Providers should cross-reference the admission hour with the medical record to ensure consistency, as payers may request supporting documentation during post-payment review. For MassHealth, all claims must be submitted electronically, so electronic validation rules will reject non-compliant submissions ^[2].

Related Codes/Fields

Code/Field	Description	Source
Admission Hour Code 00	12:00 AM - 12:59 AM	[1]
Admission Hour Code 15	03:00 PM - 03:59 PM	[1]
Admission Hour Code 17	05:00 PM - 05:59 PM	[1]
Field 13 (Admission/Start of Care Date)	Required for inpatient bills; date and hour	[1]
Midnight Rule	Determines admission date based on time	[1]
Code 23	11:00 PM - 11:59 PM	[1]

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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

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