Newsroom · Colorado

Does Medicare Cover Colonoscopy and Polyp Removal in 2026?

The screening is free. The bill, when there is one, comes from what the doctor finds while you're asleep — and that share is smaller than it used to be.

Medicare On Main Data Desk

Published August 19, 2026 · 9 min read · Reviewed by Brian Penner

The question people actually ask me is not whether Medicare covers a colonoscopy. It is why their neighbor paid nothing and they got a bill for three hundred dollars. The answer is almost never a billing error. It is a line in federal law that turns a free preventive screening into a therapeutic procedure the instant the doctor removes a polyp — and Congress has spent the last few years walking that penalty back. Here is what the 2026 rules actually say, and what to ask before you schedule.

Does Medicare cover a colonoscopy?

Yes, and the screening version is one of the most generous benefits in Part B. Most of Part B works the same way: you pay the annual deductible, then 20% of the Medicare-approved amount, forever, with no yearly maximum. A screening colonoscopy sits outside both. The statute at 42 U.S.C. 1395l(b) excludes colorectal cancer screening tests from the deductible, and preventive coverage waives the coinsurance, so a clean screening from a doctor who accepts assignment costs you nothing at all.

Sources: CMS MLN Matters MM12656 — Colorectal Cancer Screening Tests: Changes to Coinsurance for Related Procedures · 42 U.S.C. 1395l(b) — Part B deductible and the colorectal cancer screening exception · CMS: 2026 Medicare Parts A & B Premiums and Deductibles.

Two words are doing a lot of work in that sentence. Screening means the procedure was scheduled because of your age and risk, not because of a symptom. Assignment means the provider agreed to accept Medicare's approved amount as full payment. Lose either one and the arithmetic changes.

The line that produces the surprise bill

Here is the part nobody explains at the scheduling desk. You go in for a screening. The doctor finds a polyp and removes it — which is the entire point of going. That removal is a therapeutic service, and on the claim the procedure is no longer purely a screening. Before 2022 that flipped you to the full 20% Part B coinsurance, which meant the people whose screenings worked as intended were the only ones who got a bill.

Section 122 of Division CC of the Consolidated Appropriations Act, 2021 fixed it — slowly. It amended the payment statute to create a special coinsurance rule for screening colonoscopies and flexible sigmoidoscopies that become diagnostic or therapeutic, and CMS instructed contractors to apply the reduced rate regardless of the code that is billed. That last phrase matters: the reduction follows the situation, not the paperwork. And the Part B deductible stays waived either way, which is why the number on your bill is a percentage of the approved amount rather than a percentage plus $283.

The 15% is temporary — here is the schedule

This is one of the few places in Medicare where the cost of a service is legislated to fall on a fixed calendar. Per CMS, the reduced coinsurance for a procedure furnished in connection with, as a result of, or in the same clinical encounter as a colorectal cancer screening runs like this:

Your coinsurance when a screening colonoscopy becomes diagnostic

Source: CMS MLN Matters MM12656 — Colorectal Cancer Screening Tests: Changes to Coinsurance for Related Procedures, implementing Consolidated Appropriations Act, 2021 — Division CC, Section 122 (Public Law 116-260).

So a screening in December 2026 that finds a polyp is billed at 15%; the same visit in January 2027 is billed at 10%. I am not going to tell anyone to delay a colonoscopy to save five percentage points on a procedure that exists to catch cancer early — that is a bad trade in any year. But if you are already scheduling around the holidays and the date is genuinely flexible, it is worth knowing the line exists.

How often will Medicare pay for one?

The regulation, 42 CFR 410.37, counts in months, and the numbers look odd until you realize they are written to give the claims system a one-month cushion:

• Not at high risk: a screening colonoscopy after at least 119 months have passed since the last one — the ten-year interval, as a computer reads it.
• At high risk: after at least 23 months — the two-year interval.
• High risk is a defined list, not your doctor's impression: a parent, sibling or child with colorectal cancer or an adenomatous polyp; a family history of familial adenomatous polyposis or hereditary nonpolyposis colorectal cancer; your own history of adenomatous polyps or colorectal cancer; or inflammatory bowel disease, including Crohn's disease and ulcerative colitis.
• Age 45 is the floor, lowered from 50 in 2023. There is no upper age limit in the coverage rules — screening past 75 becomes a medical conversation with your doctor, not a coverage one.

If you are counting the years yourself and you land close to the line, call and ask for the date of record before the appointment. A screening submitted one month early is denied outright, and the appeal takes longer than the wait would have.

The at-home-test gap Medicare closed

For years there was a trap built into the cheaper end of colorectal screening. You did the at-home stool test — free, easy, no prep, no sedation. It came back positive. The colonoscopy you then needed was classified as diagnostic, because now there was a reason for it, and you paid the deductible and 20% for the test that was going to give you the actual answer. People declined the follow-up over the cost. That is the worst possible outcome for a screening program.

Since 2023, 42 CFR 410.37 defines a colorectal cancer screening test to include a follow-on screening colonoscopy after a Medicare-covered non-invasive stool-based test returns a positive result, and effective January 1, 2025 the same protection extends to a covered blood-based biomarker test. The follow-up is part of the screening. If a polyp comes out during it, you are back in the 15% lane for 2026 — not the full 20%.

Sedation, the facility, and the other names on the bill

A colonoscopy generates several claims from several different businesses, and each one has its own rule. Per CMS's own instruction to Medicare contractors:

• Anesthesia with a screening colonoscopy is billed under its own code, and coinsurance and deductible are waived. You do not pay for being asleep during a covered screening.
• Moderate sedation furnished with a screening colonoscopy is treated the same way — coinsurance and deductible waived.
• When the screening becomes diagnostic, the anesthesia is rebilled with a modifier showing what happened, and only the deductible is waived. The reduced coinsurance rides along with it.
• The facility bills separately from the doctor. A hospital outpatient department and a freestanding endoscopy center are paid under different Medicare payment systems, so the same procedure can produce a different dollar figure depending on the address on the door.
• Pathology is its own claim. The lab that reads the removed tissue bills you separately, and that claim follows the same reduced-coinsurance rule when it stems from a screening.

This is why "how much will this cost" is genuinely hard to answer over the phone, and why the useful question is narrower: which code is going on the claim, and does everyone touching this accept assignment?

What changes on a Medicare Advantage plan in Mesa County

An Advantage plan has to cover what Original Medicare covers, and in-network preventive services that Original Medicare provides free have to be free on the plan too. The screening should be $0 either way. Where the two systems diverge is everything around it.

On Original Medicare, any provider who accepts Medicare will do — and on the Western Slope, where people routinely drive to Grand Junction for a specialist and sometimes to Denver or Salt Lake for a subspecialist, that portability has real value. On an Advantage plan the network decides, and a colonoscopy involves at least three parties: the gastroenterologist, the facility, and the anesthesia group. All three need to participate. Intermountain Health St. Mary's Regional Hospital and Community Hospital both serve Grand Junction, but a hospital being in your network does not automatically mean every group practicing inside it is.

The second difference is the diagnostic version. The 15% figure is a federal number that applies to Original Medicare. An Advantage plan sets its own cost-sharing, which may be a flat copay instead — sometimes less, sometimes more. Get it in writing before the date, and if the plan wants prior authorization for the diagnostic code, that is a separate hurdle worth clearing early; we walked through how those approvals work in what prior authorization actually looks like in 2026.

Why this comes up so often out here

Mesa County's health profile is not dramatic, but it points the same direction the screening guidelines do. Per CDC PLACES, obesity runs 29.8% among Mesa County adults, current smoking 13.2%, and diabetes 8.1% — three of the risk factors the CDC lists for colorectal cancer, sitting in the same population that qualifies for the free screening.

Source: CDC PLACES, 2023 — via the Medicare On Main Data Desk. Model-based county estimates.

None of that is a reason to panic, and none of it is medical advice — I sell insurance, not medicine. It is a reason to notice that the one test in this category costs nothing and that the thing most likely to stop someone from having it is a rumor about a bill.

What I would check before you schedule

Five minutes on the phone before the appointment is worth more than an hour of appealing afterward. And if your bigger question is the one underneath this — whether Original Medicare with a supplement or an Advantage plan fits the way you actually use care — that is the decision this article is a small piece of, and it is laid out in Medigap vs. Medicare Advantage.

How we know all this: the Medicare On Main Data Desk frames every article with public data — here, CMS MLN Matters MM12656 on the coinsurance phase-down for procedures furnished with a colorectal cancer screening; Section 122 of Division CC of the Consolidated Appropriations Act, 2021, which created it; 42 CFR 410.37 for the frequency limits, the high-risk definition, the age 45 floor and the follow-on colonoscopy after a positive stool or blood-based test; 42 U.S.C. 1395l(b) for the deductible exclusion; CMS Transmittal R12299CP for the sedation and anesthesia rules; CMS's 2026 Parts A & B premiums and deductibles fact sheet; Medicare.gov's preventive services pages; the CDC's colorectal cancer screening guidance; and CDC PLACES county data for Mesa County — and qualitative guidance for anything priced by an individual plan or facility. We do not quote a dollar figure for a specific colonoscopy, because the Medicare-approved amount varies by procedure code and by setting, and an Advantage plan may use a copay instead of a percentage. This is education, not advice, and nothing here is medical guidance; confirm coverage, coding and cost with your doctor's office, your plan, or Medicare.gov. We take no payment from any carrier to feature a plan.