UB04 Field 12: Admission Date

Overview

Field 12 (Admission Date) on the UB-04 claim form captures the date when a patient is admitted for inpatient care or when home health care begins. This field is required for both inpatient and outpatient claims, though its primary application is for inpatient admissions and home health episodes. The admission date must be entered in MMDDYY format. ^[1]

For inpatient claims, the admission date (FL 12) must fall between the "From" and "Through" dates on the claim. Notably, the admission date can be up to 3 calendar days after the "From" date, except when the Type of Bill Frequency Code is 3 (interim bill) or 4 (final bill). This flexibility accommodates situations where the patient was admitted shortly after the billing period began. ^[2]

The Centers for Medicare & Medicaid Services (CMS) explicitly requires Field 12 for inpatient and home health claims. For home health agencies (HHAs), the admission date must match the date submitted on the Request for Anticipated Payment (RAP) for the episode. ^[3]

When to Use

Field 12 is mandatory for all inpatient hospital admissions and home health episodes. For outpatient services, while the field is technically required, its application is less critical—it typically reflects the date of service or start of care for outpatient encounters. ^[1]

The admission date must be used in conjunction with the "From" and "Through" dates on the claim. Specifically:

• The admission date must be between the "From" and "Through" dates.
• The admission date can be up to 3 calendar days after the "From" date, except when the Type of Bill Frequency Code is 3 or 4.
• For split billing scenarios (e.g., eligibility gaps, multiple approval/denial date ranges, or separate billing for sterilization/abortion services), the admission date must still align with the appropriate billing period. ^[2]

Providers should use Field 12 whenever:

• A patient is admitted for inpatient care (acute, psychiatric, rehabilitation, etc.)
• A home health episode begins
• A patient receives outpatient services requiring a start-of-care date

Step-by-Step Claim Example

Scenario: A patient is admitted to an acute care hospital on January 5, 2024, for a 3-day inpatient stay. The billing period is January 1–January 7, 2024 (Type of Bill 111).

Step 1: Enter the admission date in Field 12 as 010524 (MMDDYY format). ^[1]

Step 2: Verify the admission date falls between the "From" date (January 1) and "Through" date (January 7). Since January 5 is within this range, the claim is valid. ^[2]

Step 3: Check if the admission date is more than 3 days after the "From" date. Here, the difference is 4 days (January 5 – January 1 = 4 days). Since the Type of Bill Frequency Code is 1 (not 3 or 4), this is acceptable—the 3-day rule applies only to Frequency Codes 3 and 4. ^[2]

Step 4: For a home health episode starting February 10, 2024, enter 021024 in Field 12. Ensure this matches the admission date submitted on the RAP for the episode. ^[3]

Step 5: Complete the remaining fields (e.g., Patient Name in FL 08b, Patient Address in FL 09) as required. ^[2]

Common Mistakes & Audit Red Flags

1. Admission date outside the billing period: The most common error is entering an admission date that falls before the "From" date or after the "Through" date. This triggers claim rejection or audit scrutiny. ^[2]

2. Incorrect date format: Using YYYYMMDD or other formats instead of MMDDYY can cause data processing errors. CMS requires MMDDYY format. ^[1]

3. Mismatch with RAP for home health: If the admission date in Field 12 differs from the RAP submission date, the claim may be denied. ^[3]

4. Split billing errors: When billing for split claims (e.g., eligibility gaps or separate sterilization charges), ensure the admission date aligns with the correct billing period. Using the wrong admission date for a split claim is a red flag. ^[2]

5. Missing admission date for inpatient claims: Leaving Field 12 blank on inpatient claims will result in rejection, as it is required. ^[1]

Related Codes/Fields

Field/Code	Description	Relationship to Field 12
FL 06 (From/Through Dates)	Billing period start and end dates	Admission date must fall between these dates
FL 13 (Admission Hour)	Hour of admission	Not required; if submitted, data is ignored
FL 14 (Priority of Admission)	Type of admission (e.g., emergency, elective)	Used with admission date to determine billing rules
FL 74 (Principal Procedure Date)	Date of principal procedure	Must be between "From" and "Through" dates, similar to FL 12
Type of Bill (FL 04)	Frequency code (e.g., 1, 3, 4)	Determines if 3-day rule applies to FL 12
FL 08b (Patient Name)	Patient's full name	Required for claim processing alongside FL 12
FL 09 (Patient Address)	Patient's mailing address	Optional but recommended for accurate billing

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References

[1] CMS Chapter 25 — FL 12 — https://www.cms.gov/regulations-and-guidance/guidance/manuals/downloads/clm104c25.pdf

[2] Maryland Medicaid — FL 12 — https://health.maryland.gov/mmcp/provider/Documents/ffs-billing/UB04-Hospital-Billing-Instructions%20%281%29.pdf

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