Medicare Denied a Free Preventive Service

What This Means

Medicare covers many preventive services — like screenings, vaccines, and your annual wellness visit — at no cost to you, as long as you see a provider who accepts Medicare assignment. If you were denied coverage or charged money for a service you believe should have been free, something may have gone wrong with how it was billed.

A claim denial or unexpected charge may reflect a coding mistake, a screening that converted to treatment, a separate service, or a coverage rule. Check the code and your medical record before assuming the charge is wrong. On a denial notice you may see CARC 96 (non-covered charges).

Why This Happens

• The procedure was coded as diagnostic instead of screening. A routine Medicare screening colonoscopy is commonly billed as G0105 (high risk) or G0121 (not high risk). If it began as a screening but an unexpected finding led to treatment, the provider uses the appropriate diagnostic or therapeutic procedure code with modifier PT. Ask whether the record supports screening, conversion, or a diagnostic procedure from the start; each has different billing and cost-sharing rules.
• The applicable code or modifier was missing. Modifier PT identifies a screening colonoscopy converted to a diagnostic or therapeutic procedure. Screening anesthesia is reported with 00812, with deductible and coinsurance waived. Eligible moderate sedation billed with G0500 or 99153 uses modifier 33 for that waiver. When the screening converts to diagnostic, anesthesia is reported with 00811 and PT; the applicable moderate-sedation claim also uses PT (CMS claims guidance). Routine G0105 or G0121 screening itself does not universally require PT or 33.
• A screening converted to treatment. If a polyp was removed, Medicare phases down coinsurance: 15% in 2023–2026, 10% in 2027–2029, and 0% starting in 2030. Ask the billing office whether the therapeutic procedure carries PT and whether any separately billed anesthesia or sedation was coded under the conversion rules.
• You had the service more often than Medicare allows. Some preventive services are covered at specific intervals — for example, a screening mammogram once every 12 months, or a colonoscopy once every 10 years for average-risk patients. If you had the service sooner, Medicare may not cover it as a preventive benefit.
• The visit wasn’t coded as a wellness visit. Your annual wellness visit has its own billing codes. If the provider billed it as a standard office visit, you may be charged a copay.

Should You Appeal?

What To Do Next

1. Check the service and its coverage conditions. Use Medicare.gov’s preventive services page to confirm the screening and interval. Then compare the bill with what was actually done; treatment during a screening or a separate service may have cost-sharing.
2. Call your provider’s billing office and ask them to check the coding. Ask: “Was this a routine screening (G0105 or G0121), a screening converted to treatment (procedure code with PT), or a diagnostic test from the start? Were anesthesia or sedation billed separately, and with the applicable modifier?” If the claim does not match the record, ask for a correction.
3. Check the screening-to-treatment distinction. If a polyp was removed during a screening colonoscopy, ask whether modifier PT was applied to the converted procedure. In 2026 the procedure’s Part B coinsurance is generally 15%, with the deductible waived. A routine eligible screening has no colonoscopy cost-sharing; separate services can have different rules.
4. If the provider won’t fix it, file an appeal. Write to the address on your denial notice, include a copy of the denial, and explain that the service is a Medicare-covered preventive benefit. Reference the specific service on Medicare’s covered list.
5. Contact 1-800-MEDICARE (1-800-633-4227) or your State Health Insurance Assistance Program (SHIP) if you need help. SHIP counselors can review your statement and help you determine if the billing was correct.

Sources

• Medicare.gov: Preventive and Screening Services — the covered list and $0 cost-sharing rules
• Medicare.gov: Colonoscopies (screening) — coverage intervals and the phased reduced coinsurance when a polyp is removed (15% in 2023–2026 → 0% in 2030)
• CMS: Preventive Services Coverage
• Medicare.gov: Your Guide to Medicare Preventive Services (PDF)
• CMS: Billing and Coding — Screening Colonoscopy Converted to Diagnostic/Therapeutic
• Medicare.gov: Your Medicare Rights & Appeals

Frequently Asked Questions