Colorectal cancer is highly treatable when caught early, and a colonoscopy is one of the main tools doctors use to find it. If your doctor has recommended one — or you are simply due for routine screening — you probably want to know: does Medicare pay, and could you still end up with a bill? Medicare generally covers screening colonoscopies with no cost-sharing, but what happens during the procedure, and why it was ordered, can change what you owe. Here is how the rules work in 2026.
The Short Answer
Medicare Part B generally covers screening colonoscopies at $0 — no Part B deductible and no coinsurance — as long as your doctor or provider accepts Medicare assignment. How often Medicare covers the test depends on your risk level:
- Every 120 months (10 years) if you are at average risk for colorectal cancer
- Every 24 months (2 years) if you are at high risk — for example, because of a personal or family history of colorectal cancer or polyps, or inflammatory bowel disease
- 48 months after a flexible sigmoidoscopy, if you had that test instead
One detail that surprises many people: there is no minimum or maximum age requirement for a screening colonoscopy itself. The age-45-and-older threshold you may have heard about applies to stool-based and blood-based screening tests, which Medicare covers for people ages 45 to 85 — not to the colonoscopy.
Screening colonoscopies are part of a broader set of preventive benefits Medicare covers with no cost-sharing. For the full list, see our guide to Medicare preventive services and screenings.
When a $0 Screening Turns Into a Bill: Polyp Removal
Here is the wrinkle that generates the most surprise bills. If your doctor finds and removes a polyp or takes a tissue sample during your screening colonoscopy, the procedure is reclassified as diagnostic — and cost-sharing kicks in.
The rules have been improving, thanks to a phase-out schedule in the Consolidated Appropriations Act:
- In 2026, you pay 15% coinsurance of the Medicare-approved amount if polyps are removed during a screening. The Part B deductible is still waived.
- In 2027 through 2029, that coinsurance drops to 10%.
- In 2030, it reaches 0% — polyp removal during a screening will carry no cost-sharing at all.
One more billing detail worth knowing: if the anesthesia for your colonoscopy is billed separately, the deductible waiver still applies to it, but the anesthesia service carries the standard 20% coinsurance. If the difference between coinsurance and flat copayments is unclear, our guide to copays vs. coinsurance breaks it down.
Diagnostic Colonoscopies Cost More
If your doctor orders a colonoscopy because of symptoms — bleeding, unexplained pain, a change in bowel habits — it is a diagnostic procedure from the start, not a screening. For a diagnostic colonoscopy under Original Medicare in 2026, you generally pay:
- The Part B annual deductible of $283 (2026), if you have not already met it
- 20% coinsurance of the Medicare-approved amount
The distinction between screening and diagnostic billing comes up across many Medicare-covered tests. Our guide to Medicare lab tests and diagnostic services covers how it works more broadly.
Stool Tests and Other Screening Options — All at $0
A colonoscopy is not the only covered way to screen for colorectal cancer. Medicare covers several less invasive options with no cost-sharing:
- gFOBT and FIT stool tests — every 12 months for people 45 and older
- Cologuard (multi-target stool DNA test) — every 3 years, for people ages 45 to 85 who are at average risk and have no symptoms
- Blood-based biomarker test (such as Shield) — every 3 years, ages 45 to 85, covered since January 1, 2025
- CT colonography (virtual colonoscopy) — covered since January 1, 2025, every 5 years for average risk and every 2 years for high risk
Note that the barium enema, an older screening method, was removed from Medicare coverage as of 2025.
What if a stool or blood test comes back positive? Since January 2023, a follow-up colonoscopy after a positive stool-based test — and, since 2025, after a positive blood-based biomarker test — counts as a continuation of the screening, not a new diagnostic procedure. That means it is covered at $0, and the usual frequency limits do not apply. The one exception is the same as above: if polyps are removed during that follow-up, the 15% coinsurance (2026) applies.
How Medicare Advantage Handles Colonoscopies
Medicare Advantage plans must cover screening colonoscopies at $0 when you use in-network providers, matching Original Medicare's preventive benefit. A few plan-specific rules may apply:
- Network rules — you may need to use an in-network gastroenterologist and facility to get the $0 screening benefit
- Prior authorization may be required for some procedures, particularly diagnostic colonoscopies
- Cost-sharing for diagnostic colonoscopies varies by plan, though every Medicare Advantage plan includes an annual cap on out-of-pocket costs — see our guide to Medicare out-of-pocket limits
For a fuller picture of how these plans work, see our overview of Medicare Advantage (Part C).
Questions to Ask Before Your Procedure
A short conversation with your doctor's office can prevent billing surprises:
- Is this being scheduled as a screening or a diagnostic procedure? The answer determines your cost-sharing from the start.
- If polyps are found and removed, what will my share be? Ask for the 2026 coinsurance estimate in writing.
- Will anesthesia be billed separately, and by whom?
- Does the facility and everyone involved accept Medicare assignment? The $0 screening benefit depends on it.
How to Get Help and Learn More
If you want to confirm coverage details or talk through your options, these official resources can help:
- Medicare.gov — See the official coverage page at medicare.gov/coverage/colonoscopies.
- 1-800-MEDICARE (1-800-633-4227) — Medicare's official helpline can answer coverage and billing questions. TTY users can call 1-877-486-2048.
- State Health Insurance Assistance Program (SHIP) — SHIP offers free, unbiased counseling on what you would pay under your specific coverage. Find your local program at shiphelp.org or by calling 1-800-MEDICARE.
Summary and Next Steps
Medicare's colonoscopy coverage is generous, but the screening-versus-diagnostic distinction drives everything. Key points to remember:
- Screening colonoscopies are covered at $0 — every 120 months at average risk, every 24 months at high risk, with no age limits on the colonoscopy itself
- Polyp removal during a screening triggers 15% coinsurance in 2026 (deductible waived), dropping to 10% in 2027 and 0% by 2030
- Diagnostic colonoscopies ordered for symptoms cost the $283 deductible plus 20% coinsurance in 2026
- Stool tests, blood-based tests, and CT colonography are covered at $0 on their own schedules for ages 45 to 85
- A follow-up colonoscopy after a positive stool or blood test counts as screening — $0, with no frequency limit
- Medicare Advantage plans must cover screenings at $0 in-network, though network and prior-authorization rules may apply
If you are due for screening, talk with your doctor about which covered test fits your situation, and confirm before the procedure how it will be billed. If anything on the bill looks off afterward, your local SHIP counselor can review it with you for free.
