How Often Does Medicare Cover an MRI Scan? Costs and Appeals

Medicare sets no fixed limit on how often it will cover an MRI. There is no once-a-year rule, no six-month waiting period, and no cap on the number of scans in a lifetime. Each MRI is judged on its own: if your treating provider documents that the scan is medically necessary, Medicare will generally pay for it, whether it’s your first MRI or your fourth this year. The gatekeeper is clinical justification in your medical record, not the calendar.

What Makes an MRI Medically Necessary

Medicare’s coverage standard is that a service must be “reasonable and necessary for the diagnosis or treatment of illness or injury.” The national coverage determination for MRI treats the scan as medically effective across a broad range of uses, while flagging some applications as investigational.¹ Common accepted reasons include diagnosing a suspected condition, evaluating the severity of an injury, monitoring how a known disease is progressing, and checking whether a treatment is working.

Your provider has to document the clinical justification in your chart, including the signs, symptoms, or abnormal findings that make the scan necessary. CMS is explicit that missing documentation can result in a denied claim. The scan must also be performed on an FDA-approved MRI unit operating within its approved parameters. When the study is ordered with contrast, the gadolinium-based agent is covered as part of the study.¹

How Frequency Works in Practice

Because each MRI stands on its own clinical justification, a patient can be covered for repeat scans in quick succession. If an oncologist wants to check tumor response every three months, Medicare will generally cover all four annual scans. If a neurologist orders a second brain MRI within a week because new symptoms appeared after the first, that can be covered too.

The one wrinkle is that national or local coverage policies sometimes set frequency expectations for specific MRI types. A claim that exceeds those expectations can be denied unless the provider submits documentation justifying the higher frequency.¹ If your doctor explains in the record why the scan was needed sooner than the typical interval, Medicare has a basis for approving the claim.

Prior Authorization Under Medicare Advantage

Original Medicare does not require prior authorization for an MRI. Your doctor orders it, you get it, and the claim is submitted afterward. Medicare Advantage is different. Many MA plans require prior authorization for imaging, which means your doctor’s office must get the plan’s approval before the scan happens. If you’re getting frequent MRIs, this is where friction shows up.

CMS has placed guardrails on how MA plans use prior authorization. Plans may only use it to confirm diagnoses or medical criteria and to verify medical necessity, and they cannot require it for emergency or urgently needed services.² Standard requests must get a response within 7 calendar days; urgent requests within 72 hours.³ If the plan denies the request, the denial must be in writing, and you can appeal through the plan’s internal process. CMS also requires MA plans to run a Utilization Management Committee that reviews prior authorization policies annually to keep them consistent with Original Medicare’s coverage decisions.

What You Pay Per Scan

An outpatient MRI is covered under Medicare Part B, which lists diagnostic non-laboratory tests among its covered services.⁴ Under Original Medicare, you first meet the annual Part B deductible of $283 in 2026.⁵ After that, Medicare pays 80% of the approved amount and you owe the remaining 20% as coinsurance. If you’re getting scans on an ongoing basis, that 20% adds up.

The setting matters. If you get the MRI at a hospital outpatient department rather than your doctor’s office or a freestanding imaging center, you also face a hospital copayment. That copayment can exceed 20% of the approved amount, though it generally cannot be more than the Part A inpatient deductible, which is $1,736 in 2026.⁴⁵ The same scan can cost noticeably more at a hospital outpatient facility than at a freestanding center. If you have a choice, asking your doctor for a referral to a freestanding center can save real money.

If the provider performing the MRI does not accept Medicare assignment, they can charge up to 15% above the Medicare-approved amount, called the limiting charge.⁶ Confirm the facility accepts assignment before scheduling. A Medicare Supplement (Medigap) policy covers most or all of the 20% Part B coinsurance depending on the plan letter, which is worth knowing if repeat imaging is in your future. Medicare Advantage plans set their own copayments for MRIs, and those amounts can be lower or higher than 20%; check your plan’s evidence of coverage, and note whether in-network and out-of-network rates differ.

When a Provider Warns You With an ABN

If a provider suspects Medicare will not pay for a particular MRI, whether because it exceeds the typical frequency for your diagnosis or the indication is in a gray area, they are required to give you an Advance Beneficiary Notice of Noncoverage (ABN) before performing the scan. The ABN tells you Medicare may deny the charge and asks whether you want to proceed and accept financial responsibility.⁷ Situations that trigger it include care that isn’t reasonable and necessary for your diagnosis, services that exceed Medicare’s allowed frequency, and experimental uses of MRI.⁸

The protection is real. If a provider fails to give you a required ABN and Medicare later denies the claim, the provider may be held financially liable, not you.⁸ If you never signed an ABN and a bill shows up for a denied MRI, push back.

Appealing a Denied MRI

When Original Medicare denies an MRI claim, the denial appears on your Medicare Summary Notice. Medicare Advantage enrollees receive an Explanation of Benefits from their plan.⁹ Either one explains the reason.

Before appealing, call your doctor’s office. Denials often come from coding errors or missing documentation, and a resubmission with corrected information can resolve it without a formal appeal.

If the denial stands, Medicare offers a five-level appeal process.¹⁰ The first level, redetermination, is a review by the Medicare Administrative Contractor, and you have 120 days from the date you receive the initial denial to file.¹¹ Medicare presumes you received the notice five days after its date, so count from that presumed receipt. If redetermination doesn’t go your way, the second level is reconsideration by a Qualified Independent Contractor, filed within 180 days. Higher levels include an Administrative Law Judge hearing, Medicare Appeals Council review, and finally federal court, each with its own filing deadline and minimum dollar threshold.

Most MRI denials are resolved at the first or second level. The single strongest document to submit is a letter from your treating physician explaining exactly why the scan was medically necessary, together with the relevant medical records. That’s the same documentation that would have prevented the denial in the first place, and it’s the same standard that governs how often Medicare will cover the next MRI, and the one after that.

1
Centers for Medicare & Medicaid Services. NCD – Magnetic Resonance Imaging (220.2)
2
Centers for Medicare & Medicaid Services. 2024 Medicare Advantage and Part D Final Rule (CMS-4201-F)
3
Federal Register. Medicare and Medicaid Programs – Patient Protection and Affordable Care Act – Advancing Interoperability
4
Medicare.gov. Diagnostic Non-Laboratory Tests
5
Centers for Medicare & Medicaid Services. 2026 Medicare Parts A and B Premiums and Deductibles
6
Medicare. Does Your Provider Accept Medicare as Full Payment
7
Centers for Medicare & Medicaid Services. FFS ABN
8
Centers For Medicare & Medicaid Services. Advance Beneficiary Notice of Non-coverage Tutorial
9
Medicare.gov. Medicare Summary Notice (MSN)
10
Medicare.gov. Filing an Appeal
11
Centers for Medicare & Medicaid Services. First Level of Appeal – Redetermination by a Medicare Contractor