90 Day Global Period Calculator: Major Surgery Follow-Up Dates
Major surgical procedures carry a 090 global indicator, meaning the fee already covers one pre-operative day, the surgery, and 90 days of routine post-operative care. Knowing the exact end date tells you when normal visits become billable again.
How the 90 days are counted
The count begins the day after surgery and runs 90 consecutive calendar days. That means the global window is 92 days wide in total: the pre-operative day, the day of surgery, and the 90 post-operative days. Weekends and public holidays are included, and no adjustment is made for the number of days in the months involved.
Common 90-day examples
- Surgery 2 October 2025 — global period 1 October 2025 to 31 December 2025.
- Surgery 28 July 2025 — global period 27 July 2025 to 26 October 2025.
- Surgery 1 January 2026 — global period 31 December 2025 to 1 April 2026.
Why 90 days is not three months
Ninety days is shorter than three calendar months in almost every case, because most months run 30 or 31 days. Billing from a mental three-month rule pushes the end date two to three days late and risks submitting a claim that Medicare will bundle into the surgical package. Use the calendar-day count from the surgery date every time.
Transfer of care within the global
When one physician performs the surgery and another provides the follow-up, the global fee is split with modifiers 54 (surgical care only) and 55 (post-operative management only), each reporting the dates they assumed care. Modifier 56 covers pre-operative management only. The 90-day clock itself does not change when care is transferred.
Key takeaways — 90 Day Global Period Calculator
- 090 global = day before surgery, day of surgery, plus 90 post-operative calendar days.
- Ninety days is two to three days short of three calendar months.
- Split care between surgeons is billed with modifiers 54, 55 and 56 within the same window.