Which year’s rates apply? Discharge dates, the October 1 line and grouper versions

The short answer

• Inpatient claims: the discharge date decides. It sets the fiscal year’s rates, the MS-DRG grouper and code-editor version, and which ICD-10 codes are valid. The admission date does not pick the rate year, the grouper or the code set; it still sets the length of stay. A stay admitted September 28 and discharged October 3, 2026 is an FY2027 claim from start to finish.
• Outpatient claims (hospital outpatient and ASC): the date of each line decides. Rates are set by calendar year, and each line prices at the rates for the year of its own date of service. CMS republishes the tables each quarter, mostly for drugs and new codes; cmswebpricer.com prices a year’s facility lines on one release of that year’s tables (for 2026, the October 2026 release of Addendum B), and only Part B drug prices on professional claims follow the quarter of the date of service. Medicare contractors require hospitals to split an outpatient claim that crosses December 31; they do not require a split at October 1.

For an inpatient stay the discharge date picks the year, the grouper and the code set. The admission date only counts the days.

One stay, two fiscal years

Here is the same claim at NewYork-Presbyterian Hospital, MS-DRG 871, eight days and $520,000 in covered charges, priced with two discharge dates a day apart:

Every input moved at once: the DRG weight, the hospital’s wage index, the base rates and the outlier fixed-loss amount. This is a high-cost stay, and the smaller outlier more than accounts for the $10,300.23 difference: before the outlier, the stay pays $831.47 more on October 1. Our FY2027 rate article breaks it down line by line.

Grouper versions follow the discharge date too

Each fiscal year’s MS-DRG grouper takes effect on October 1. In each of the last five years CMS has also released an April 1 version, the “.1” release, that adds new diagnosis and procedure codes mid-year.

A repricer that regroups claims should pick the version from the discharge date, not from the date the claim arrives. The claim import on this site does that and says which version it used: a sample claim discharged October 15, 2026 comes back “Grouped under v44, the manual in force on 2026-10-15.”

Edge cases worth a rule

• Stays that cross October 1. Priced and grouped entirely under the new year, with codes that are valid on the discharge date.
• The hospital’s own record. Wage index reclassifications, cost-to-charge ratios and other provider factors can change during the year. Price with the record in force on the discharge date, as this engine does.
• Late claims. Medicare accepts claims up to a year after the date of service, so FY2026 tables stay in use well into FY2027.
• Outpatient observation. When observation spans more than one calendar day, all its hours go on one line dated the day observation began.
• Outpatient visits at year end. A visit that starts December 31 and ends January 1 is split into two claims, one for each calendar year. A visit that crosses October 1 stays on one claim. The January rates also move the gap between hospital outpatient and ASC payment for the same procedure (the site-of-service gap).

A date checklist for claim systems

1. Store the admission date, discharge date and statement dates separately, and derive the length of stay as the discharge date minus the admission date.
2. Select inpatient rate tables and grouper versions by discharge date, never by the date the claim was received or processed.
3. Keep at least two inpatient rate years live.
4. Price outpatient lines at the rates for the calendar year of their own dates of service, and expect year-end splits.
5. Show the rate year and grouper version on every priced claim, so a reviewer can see which rules applied.