Global Surgery Period Calculator (10-Day & 90-Day CMS Billing)
Calculate the exact CMS Medicare postoperative global surgical package start date, end date, and first billable E/M follow-up date for 000, 010, and 090 CPT codes.
How to Use the Global Surgery Period Calculator (10-Day & 90-Day CMS Billing)
In medical coding and CMS Medicare Physician Fee Schedule billing, the Global Surgical Package bundles preoperative, intraoperative, and routine postoperative Evaluation and Management (E/M) visits into a single global surgical reimbursement. Counting post-op days accurately prevents costly claim denials and improper unbundling audits.
Formula and Calculation Methodology
- 090 Major Surgery: 92 total days: 1 day prior to surgery + day of surgery + 90 consecutive days after surgery
- 010 Minor Surgery: 11 total days: day of surgery + 10 consecutive calendar days immediately following surgery
- 000 Procedure: 1 day: only E/M services on the exact date of the procedure are bundled
Under official CMS counting rules, the day of the surgical procedure itself is Day 0, and Day 1 of the postoperative period begins on the calendar day immediately following surgery. Consequently, a 10-day minor surgical global period (010) spans 11 total calendar days (the surgery date plus 10 post-op days), while a 90-day major surgical global period (090) spans 92 total calendar days (1 preoperative day, the surgery date, and 90 post-op days).
CMS Global Surgery Modifiers for Billing During the Post-Op Window
| CPT Modifier | Modifier Name | When to Append within Global Period |
|---|---|---|
| Modifier 24 | Unrelated E/M by Same Physician | Office visit during post-op for an unrelated diagnosis |
| Modifier 25 | Significant, Separately Identifiable E/M | Same-day E/M that led to a minor (000/010) procedure |
| Modifier 57 | Decision for Surgery | E/M visit the day before or day of a major (090) surgery |
| Modifier 58 | Staged or Related Procedure | Planned staged procedure during the post-op period |
| Modifier 78 | Unplanned Return to OR | Related surgical complication requiring return to operating room |
| Modifier 79 | Unrelated Procedure by Same Physician | Completely unrelated surgery during the post-op period |
Frequently Asked Questions
Does the day of surgery count as Day 1 of the 90-day global period?
No. CMS counts the date of surgery as the intraoperative service day, and the 90 postoperative days begin the calendar day AFTER surgery (so a major surgery package covers 1 pre-op day + 1 surgery day + 90 post-op days = 92 days).
Can I bill an office visit during a 90-day global period?
Routine post-op follow-ups (suture removal, dressing changes, pain checks) are bundled and cannot be billed separately. However, if the visit is for a completely unrelated condition, you can bill the E/M with Modifier 24.
What modifier is used for the E/M visit where the decision for a major surgery is made?
If the decision to perform a major (090) surgery occurs on the day before or the day of the surgery, append Modifier 57 (‘Decision for Surgery’) to the E/M code so it is not bundled into the pre-op package.