Newsroom · Sioux Falls

Does Medicare cover colonoscopy? What happens the moment they find a polyp, Sioux Falls 2026

The screening is free by federal rule. The moment a polyp comes out, a second, different rule takes over — and it's the one nobody explains at check-in.

Big Sioux Benefits Data Desk

Published August 15, 2026 · 14 min read · Sourced from Medicare.gov and CMS.gov

A Medicare screening colonoscopy really is free — no deductible, no coinsurance, guaranteed by federal rule. The bill that sometimes follows isn't a mistake. It's a second rule that switches on the instant a polyp is found and removed, splitting one procedure into two different billing outcomes without you ever leaving the table. Nobody explains that split at check-in, because nobody can know in advance which outcome you're going to get.

Here's the shape of it: you schedule what your doctor's office calls a routine screening. You do the prep, you show up, you go under sedation. If the doctor sees nothing, the exam ends and the bill is $0, exactly as advertised. If the doctor sees a polyp — which happens often enough that it's the whole point of the exam — removing it right then, in the same procedure, is standard practice and the outcome you actually want. But the instant that happens, Medicare's own coding rules reclassify part of what you just had done from a screening test into a diagnostic and therapeutic one. That reclassification carries a coinsurance charge. You agreed to a screening. You may walk out having also received, and owed money for, something else.

Every figure in this guide comes from a source fetched and confirmed this week: Medicare.gov's colonoscopy coverage page, the Federal Register's CY2022 Physician Fee Schedule final rule, CMS Transmittal MM12656, CMS's 2026 Parts A & B premiums and deductibles fact sheet, and the American Cancer Society's own summary of Medicare screening coverage. No invented numbers, nothing pulled from memory.

What Medicare actually covers for colorectal cancer screening

Colonoscopy isn't the only screening test Medicare pays for, and it isn't always the first one your doctor will suggest. Medicare Part B covers five distinct colorectal cancer screening options, each on its own frequency clock, and every one of them is $0 at the point you take it — no deductible, no coinsurance — as long as your provider accepts assignment, per Medicare.gov.

Source: Medicare.gov, Colonoscopies, Multi-target stool DNA tests, Blood-based biomarker tests, and Fecal occult blood tests, all verified 2026.

Average risk means no personal history of polyps, colorectal cancer, or inflammatory bowel disease, and no family history of colorectal cancer or related hereditary syndromes — that's the group eligible for the stool DNA test, the blood-based test, and the 10-year colonoscopy interval. High risk covers people with a personal or family history along those lines, and it's the group Medicare moves to a 24-month colonoscopy interval instead of 10 years. Your own doctor determines which category you're in; it isn't a box you check yourself.

Who this covers, and starting when

Colorectal cancer screening got a real, relatively recent change worth knowing about: the U.S. Preventive Services Task Force now recommends people at average risk start screening at age 45, down from the age-50 standard that stood for decades, according to the American Cancer Society. Medicare's own coverage rules for the stool DNA test, the blood-based biomarker test, and the fecal occult blood test all use that same 45-and-older starting line. If you're on Medicare due to a disability before your 65th birthday and you're 45 or older, that starting age already applies to you.

Screening colonoscopy is the one exception worth noting, and it runs the other direction: Medicare.gov states plainly that there's no minimum age requirement to get a screening colonoscopy at all. In practice, most people encounter this benefit around 45 to 50, whenever their doctor recommends starting, or earlier if a family history or a specific medical condition puts them in the high-risk category with its own 2-year interval. There's also no published maximum age on Medicare.gov — the decision to continue screening in your 80s or beyond is a conversation with your doctor about your own health, not a hard federal cutoff.

None of that changes the billing mechanic described in this guide. Whether you're 46 or 86, whether this is your first colonoscopy or your fifth, the same rule applies the moment a polyp comes out: the screening stays free, and the removal is billed separately.

Why a "free" screening can turn into a bill

Medicare draws a hard line between two kinds of medical services: screening, which looks for a problem in someone who has no symptoms and hasn't been diagnosed with one, and diagnostic or therapeutic care, which addresses a problem that's actually been found. A colonoscopy starts life as the first kind. The instant a physician identifies tissue — a polyp, in most cases — and removes it, the part of the procedure that did the removing gets coded as the second kind, even though it happened in the same room, under the same sedation, during the same appointment you booked as a screening.

This isn't a loophole or an accident of paperwork. It's how the billing code set is built. A colonoscopy where nothing is found is billed under a screening code. A colonoscopy where a polyp is found and removed by snare, forceps, or another technique is billed, for that portion, under a different procedure code — one that Medicare has always treated as diagnostic, because removing tissue is treatment, not observation. Congress and CMS added a special coinsurance rule specifically for this scenario; without it, that diagnostic portion would carry the full standard 20% Part B coinsurance instead of the reduced rate described below.

It's worth knowing where that reduced rate came from, because it wasn't always this favorable. For calendar year 2022, the phase-down described in the next section started at the full 20% — the same rate Part B charges for most other outpatient services — before stepping down to 15% in 2023, per the Federal Register text of the rule itself. Congress built the whole phase-down into the Consolidated Appropriations Act specifically because a full 20% surprise coinsurance charge, on top of a procedure people had been told was free, was discouraging some beneficiaries from completing colorectal cancer screening at all. The rule you're reading about now is the fix, already several years into a gradual rollout toward zero.

The screening-to-diagnostic mechanic, in plain terms

When a polyp is found and removed during a screening colonoscopy, the billing office attaches what's known in Medicare claims processing as the PT modifier to the procedure code. That modifier tells Medicare: this claim started as a screening test and became something more during the same encounter. The PT modifier is the mechanism that keeps your Part B deductible waived even though part of the visit is now diagnostic — without it, you could theoretically owe both the deductible and the coinsurance. With it, per CMS's own transmittal guidance, you owe only the coinsurance.

Walk through what that looks like without inventing a dollar figure we haven't verified: you go in for your 10-year screening colonoscopy. The physician finds a single polyp and removes it with a snare. The claim gets split — the screening portion stays at $0, and the polypectomy portion gets the PT modifier and a 15% coinsurance charge in 2026, calculated against the Medicare-approved amount for that specific procedure code. If the exam happens in a hospital outpatient department or an ambulatory surgical center rather than a physician's office, a separate 15% facility coinsurance applies on top of the provider's charge, per Medicare.gov. Two different bills can come out of one appointment: your provider's portion and, depending on where the procedure happened, the facility's portion.

The coinsurance math for 2026, and the phase-down schedule

The 15% figure isn't permanent, and it isn't arbitrary. Congress wrote a phase-down into the Consolidated Appropriations Act, and CMS finalized the exact schedule in its Calendar Year 2022 Physician Fee Schedule final rule, published in the Federal Register. The coinsurance on a screening test that becomes diagnostic runs at 15% for dates of service in 2023 through 2026, drops to 10% for 2027 through 2029, and disappears entirely — 0% — starting in 2030. CMS Transmittal MM12656, the claims-processing guidance sent to every Medicare contractor, confirms the identical schedule independently.

The American Cancer Society independently confirms the same figure in its own summary of Medicare coverage rules — a third source, alongside the two CMS documents above, all agreeing on the same 15% number for 2026.

Source: Federal Register — CY 2022 Physician Fee Schedule Final Rule (CMS-1751-F), §II.I and CMS Transmittal MM12656 — Colorectal Cancer Screening Tests.

The 2026 cost-sharing figures for context, both from CMS's Parts A & B premiums and deductibles fact sheet released November 14, 2025: the standard Part B monthly premium is $202.90, and the Part B annual deductible is $283. Neither figure applies directly to a screening colonoscopy — the deductible is waived for this specific procedure whether or not a polyp is removed — but they're the backdrop for every other Part B service you use during the year, and they're the numbers a coinsurance percentage gets calculated against.

Do the non-invasive tests avoid this risk?

Partly, and only for a while. A stool DNA test, a blood-based biomarker test, and a fecal occult blood test are each $0 to take, and none of them involves sedation, a facility fee, or the possibility of a same-day coinsurance charge — you take the test, mail it in or get the blood draw, and the result comes back positive or negative. If it's negative, you're done until your next scheduled test. If it's positive, Medicare requires a follow-up colonoscopy, and — importantly — Medicare.gov classifies that follow-up exam as a screening test too, not a diagnostic one triggered by symptoms. That's a real, separate rule CMS put in place specifically so a positive stool or blood test doesn't discourage anyone from completing the process with a colonoscopy.

Here's the catch: once you're in that follow-up colonoscopy, you're back inside the exact same screening-to-diagnostic mechanic described above. If the doctor finds and removes a polyp during the follow-up exam, the same 15% coinsurance in 2026 applies to that portion, for the same reason it would in a first-line screening colonoscopy. Choosing a stool or blood test first doesn't eliminate the risk of ever owing this coinsurance — it just means you only face it if that initial test comes back positive, rather than facing it during a routine 10-year exam that might turn something up anyway.

For someone who is genuinely undecided among the options, that's a real, honest trade-off to weigh with your doctor: the stool and blood tests are less invasive and carry zero procedure risk up front, but a positive result still routes you to a colonoscopy in the end. A first-line colonoscopy is more invasive up front but settles the question — clear or not — in one visit, with the small chance of that same coinsurance if something's found and removed.

What to ask before you schedule

You don't need to become a coding expert to protect yourself here. Three questions, asked before the day of the procedure, cover almost everything that matters.

Medicare's own Procedure Price Lookup tool is built for exactly this — national average costs for outpatient procedures, broken out by facility type. It won't replace your provider's actual bill, but it gives you a real number to compare their estimate against before you agree to anything, the same way we'd point you to it for any other outpatient procedure.

How Medigap and Medicare Advantage change what you owe

If you have Original Medicare alone, the coinsurance described above — 15% in 2026 — comes straight out of your pocket if a polyp is removed. Adding a Medicare Supplement (Medigap) policy changes who pays it, not whether it's owed in the first place.

Source: CMS Publication 02110, Choosing a Medigap Policy, standardized plan benefits under 42 CFR §403.205.

Both plans leave the Part B deductible itself untouched for your other Part B services during the year — remember, the deductible is already waived specifically for the colonoscopy, so that's not where Medigap does its work here. Where it matters is the 15% coinsurance on the polyp-removal portion: with Plan G or Plan N, that charge routes to the supplement instead of your checking account.

If you're on a Medicare Advantage plan instead, federal rule requires it to cover the same preventive colorectal cancer screenings Original Medicare covers, generally at $0 in-network. The screening-to-diagnostic mechanic still exists on Medicare Advantage — a polyp removal is still a distinct, billable event — but what you owe is governed by your specific plan's cost-sharing structure and its annual out-of-pocket maximum, not the 15% Part B coinsurance rate described above. That's one more reason your plan's Evidence of Coverage, not a general rule of thumb, is the document that actually answers what a polyp removal would cost you.

The Sioux Falls picture

South Dakota's colorectal cancer screening rate among adults ages 45-75 was 66.9% in 2024, according to America's Health Rankings — meaning roughly a third of the eligible population hadn't completed a recommended screening within the interval their risk level calls for. Minnehaha County carries 39,532 Medicare beneficiaries, per CMS county enrollment data, a population where colorectal cancer screening is squarely within the age range Medicare covers for nearly everyone on the list.

Sioux Falls care runs through two hospital systems, and the billing mechanics described in this guide apply at both — the PT modifier and the coinsurance phase-down are federal Medicare rules, not hospital-system policy. CMS's Hospital Compare rates Sanford USD Medical Center at 5 stars and Avera McKennan Hospital & University Health Center at 4 stars — whichever system your gastroenterologist or primary care clinic sits inside, the same screening-versus-diagnostic distinction governs your bill.

Minnehaha County's 5 standard Medicare Advantage PPOs, open to anyone with Medicare in the county, are shown below with their current premiums and CMS star ratings:

Source: CMS Medicare Advantage / Part D Landscape (PY2026) & CMS Medicare Advantage & Part D Star Ratings (2026), Minnehaha County, plan year 2026.

See the full Sioux Falls Medicare plan comparison for details on each option. Whether you're on Original Medicare or one of the plans we offer in the Sioux Falls area, the screening rule is federal and identical either way. What changes between plans is exactly what's described above: Original Medicare charges the 15% Part B coinsurance if a polyp is removed, Medigap Plan G or Plan N can pick that up for you, and a Medicare Advantage plan applies its own cost-sharing and annual out-of-pocket maximum instead.

What to do if the bill already came

If a bill or a Medicare Summary Notice already arrived and the amount surprised you, start by reading it line by line. Look for the procedure code tied to your colonoscopy alongside a second code for a polypectomy or biopsy, and check whether the PT modifier appears next to it. If it's there, the billing very likely followed the rule described in this guide, even if nobody explained it to you beforehand.

It's worth saying plainly: most of these bills are correct. This guide isn't about teaching you to dispute a legitimate charge — it's about recognizing the difference between a genuine billing error and a normal, documented consequence of a good medical outcome. Both happen. Only one is worth pushing back on.

1. Call the billing office first. Ask what the PT modifier and the diagnostic code cover on your specific claim. Most questions get answered here, in one call.
2. Compare it to what happened in the room. Did the doctor remove a polyp, take a biopsy, or otherwise treat something they found? If nothing was removed and you're still being billed as diagnostic, that's worth questioning directly.
3. Request an itemized statement if the explanation doesn't add up, separating the provider charge from any facility charge.
4. File a formal appeal if the office can't resolve it. Original Medicare and Medicare Advantage each have a defined appeals process with real deadlines.

You don't have to work through this alone. Most people find the paperwork is the part they'd rather have a second pair of eyes on — book a conversation and we'll go through the notice with you, no cost, no obligation.

What to watch for 2027 and beyond

1. The coinsurance rate steps down to 10% for dates of service starting January 1, 2027 — mark it if you're weighing when to schedule a discretionary follow-up.
2. Confirm your risk category with your doctor before assuming your interval is 10 years — a family history can move you to a 2-year cycle you may not know applies to you.
3. Ask about the PT modifier by name when you schedule, not after the bill arrives.
4. Check your Medicare Summary Notice or EOB after any colonoscopy, whether or not you expected a bill.
5. If you're choosing between a stool test and a colonoscopy, ask your doctor which fits your risk category and your own preference — both are legitimate, sourced, $0 starting points.

How we know all this: Big Sioux Benefits runs every article through a data desk that cross-references Medicare.gov's coverage rules, the Federal Register and CMS transmittal guidance on the colorectal cancer screening coinsurance phase-down, the 2026 CMS Parts A & B cost-sharing fact sheet, the Minnehaha County Medicare Advantage plan landscape, CMS Hospital Compare, and America's Health Rankings — built by Strategic AI Architects. Every figure here is sourced and dated. This is education, not medical or legal advice; confirm your specific bill with your provider's billing office or Medicare.gov, and confirm plan details with a licensed agent. We take no payment from any carrier to feature a plan, and Big Sioux Benefits is a licensed independent insurance agency, not connected with or endorsed by the United States government or the federal Medicare program. We do not offer every plan available in your area — any information we provide is limited to those plans we do offer in your area. Contact Medicare.gov, 1-800-MEDICARE, or your local State Health Insurance Program (SHIP) for information on all of your options.