UB04 Admission Hour Code 18: 06:00 PM - 06:59 PM

Overview

Code 18 on the UB-04 claim form represents the admission hour of 06:00 PM to 06:59 PM in military time. This code is used to indicate the specific hour when a patient was admitted for inpatient care or when outpatient care began. According to CMS guidelines, the admission hour code must be a two-digit number from 00 to 23, where 00 represents midnight (12:00 AM) and 23 represents 11:00 PM. Code 18 specifically corresponds to the hour between 6:00 PM and 6:59 PM. ^[1]

The admission hour code is entered in Field 13 of the UB-04 form, which is titled "Admission/Start of Care Date." This field is required on inpatient bills only and must include both the date of admission and the hour of admission. The hour is expressed in military time format, meaning Code 18 represents the 18th hour of the day, which is 6:00 PM. ^[1]

MassHealth requires that all claims be submitted electronically unless the provider has received an approved electronic claim submission waiver. The UB-04 billing guide provides detailed instructions for completing the paper claim form, including proper use of code sets like admission hour codes. ^[2]

When to Use

Use Code 18 when the patient's admission or start of care occurred at any time between 6:00 PM and 6:59 PM. This includes both inpatient admissions and outpatient care starts that fall within this one-hour window. The code must be entered in military time format as a two-digit number in Field 13 of the UB-04 claim form. ^[1]

This code is specifically required on inpatient bills only, as Field 13 is mandatory for inpatient claims. For outpatient claims, the admission hour code may still be used but is not always required depending on payer specifications. The hour code should reflect the exact hour when the patient was physically admitted or when outpatient care services began. ^[1]

MassHealth providers should note that while the UB-04 form includes this field, all claims must be submitted electronically unless a waiver has been granted. The electronic submission process still requires accurate coding of admission hour information. ^[2]

Step-by-Step Claim Example

Scenario: A patient is admitted to the hospital at 6:30 PM on March 15, 2024.

Step 1: Locate Field 13 on the UB-04 claim form. This field is titled "Admission/Start of Care Date." ^[1]

Step 2: Enter the admission date in the date portion of Field 13. For this example, enter "03/15/2024" as the date of admission. ^[1]

Step 3: Enter the admission hour code in the hour portion of Field 13. Since the admission occurred at 6:30 PM, which falls within the 6:00 PM to 6:59 PM hour, use Code 18. Enter "18" in the two-digit hour field. ^[1]

Step 4: Verify the entry. The completed Field 13 should show "03/15/2024 18" indicating admission on March 15, 2024, at 6:00 PM to 6:59 PM. ^[1]

Step 5: For MassHealth claims, submit the claim electronically through the approved electronic claims system. The admission hour code will be transmitted as part of the electronic data. ^[2]

Common Mistakes & Audit Red Flags

Mistake 1: Using 12-hour clock format. Providers sometimes mistakenly enter "6" or "06" instead of "18" for 6:00 PM. Remember that all admission hour codes must be in military time format (00-23). Code 18 is the correct representation for 6:00 PM to 6:59 PM. ^[1]

Mistake 2: Confusing AM and PM. A common error is using Code 06 (6:00 AM) instead of Code 18 (6:00 PM). Double-check that the hour code matches the actual time of day, especially for evening admissions. ^[1]

Mistake 3: Omitting the hour code entirely. Some providers leave the hour field blank or enter only the date. Field 13 requires both the date and the hour code for inpatient claims. Missing hour codes can result in claim rejections or delays. ^[1]

Audit Red Flag: Inconsistent admission times across multiple claims for the same patient. If a patient's admission hour code shows 18 (6:00 PM) but other documentation shows a different time, auditors may flag this for review. Ensure the hour code matches the actual admission time recorded in medical records. ^[1]

Audit Red Flag: Using Code 18 for outpatient services when the service started at a different hour. The admission hour code must reflect the exact hour when care began, not an estimated or rounded time. ^[1]

Related Codes/Fields

Code/Field	Description	Source
Code 00	12:00 AM (midnight)	[1]
Code 01	1:00 AM - 1:59 AM	[1]
Code 06	6:00 AM - 6:59 AM	[1]
Code 17	5:00 PM - 5:59 PM	[1]
Code 18	6:00 PM - 6:59 PM	[1]
Code 19	7:00 PM - 7:59 PM	[1]
Code 23	11:00 PM - 11:59 PM	[1]
Field 13	Admission/Start of Care Date	[1]
Field 12	Patient Control Number	[2]
Field 14	Type of Admission/Visit	[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