Medicare Assignment: What It Means and What You Pay

Medicare assignment is an agreement. A provider who accepts assignment agrees to take the amount Medicare approves as full payment for a covered service. You then owe only your deductible and coinsurance. A provider who doesn’t accept assignment can bill you more, which is where surprise charges come from. Here is how it works, how to check before a visit, and what to do if a bill looks too high.

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TL;DR

• Accepting assignment means the provider takes the Medicare-approved amount as payment in full and bills Medicare directly.
• With an assigned claim, you typically pay 20% of the approved amount after your Part B deductible, which is $283 in 2026.
• Non-participating providers who don’t accept assignment can charge up to 15% above the approved amount for most Part B services. That extra is called balance billing, or an excess charge.
• Assignment applies to Original Medicare. It doesn’t apply the same way in a Medicare Advantage plan.
• Ask before you book: “Do you accept Medicare assignment?”

Table of Contents

• What Medicare assignment means
• What you pay when a provider accepts assignment
• Participating vs. non-participating providers
• Balance billing and excess charges
• How to check before you book
• Does assignment apply to Medicare Advantage?
• Our perspective
• Get help matching your plan to your doctors
• FAQ
• Sources

What Medicare assignment means

When Medicare covers a service, it doesn’t pay whatever a provider decides to charge. It sets an approved amount for each service. Assignment is the provider’s agreement to treat that approved amount as the full price. Medicare’s own benefits booklet describes it as an agreement to be paid directly by Medicare, accept the approved payment as payment in full, and not bill you for more than the deductible and coinsurance.

You may also see the phrase “assignment of benefits.” In Medicare, that’s the same idea seen from the patient’s side: you let Medicare pay the provider directly rather than paying up front and waiting for reimbursement. AARP’s explainer frames it as accepting no more than the Medicare-approved amount for the service.

Two points often confuse people:

• Accepting Medicare is not the same as accepting assignment. A doctor can take Medicare patients and still decline assignment on a given claim.
• Assignment is about Part B-type services. Doctors, outpatient care, and many supplies are where it matters most.

What you pay when a provider accepts assignment

This is the best case for your wallet. Medicare says you get the lowest cost when your doctor accepts the Medicare-approved amount as full payment.

The provider also submits the claim for you. Per CMS’s glossary, Medicare pays 80% of the approved amount, less any unmet deductible. The provider can charge you only the remaining 20% coinsurance.

Here is a simple example with made-up round numbers. Suppose Medicare approves $200 for an office visit and you have already met your deductible:

Step Amount Medicare-approved amount $200 Medicare pays 80% $160 You pay 20% coinsurance $40 Total the provider can collect $200

If you haven’t met the 2026 Part B deductible of $283, you pay toward that first. If you have a Medicare Supplement (Medigap) plan, it may cover some or all of that 20%, depending on the plan letter. Our guide to copays versus coinsurance explains why the two behave differently.

Participating vs. non-participating providers

Providers choose how they work with Medicare. There are three main paths.

Participating (PAR) Non-participating (non-PAR) Opted out Accepts assignment On every claim Case by case No Can charge above approved amount No Up to the limiting charge on unassigned claims Whatever they set, under a private contract Who bills Medicare Provider Provider should still submit Nobody, Medicare doesn’t pay Your risk Lowest Possible excess charge Full cost for non-emergency care

Participating providers

CMS explains that participating providers agree to accept assignment on all claims for all covered services. They accept Medicare-allowed amounts as payment in full and can’t collect more than the deductible and coinsurance or copayment. The AAFP adds that this commitment lasts for the calendar year.

Non-participating providers

Non-participating providers can still treat Medicare patients, and they may accept assignment on some claims. When they don’t, they can bill above the approved amount, but only up to the limiting charge. CMS describes that as 115% of the fee schedule amount for non-participating suppliers. Medicare’s booklet puts it as 15% over the approved amount for most Part B services.

Participation decisions are made annually. CMS notes that the decision window for the coming year runs from mid-November through December 31. So a provider’s status can change from one January to the next.

Opt-out providers

Opt-out is a different category. Illinois Legal Aid Online explains that these providers don’t accept Medicare at all, can charge what they like, and Medicare won’t cover their non-emergency services. You sign a private contract first, so read it carefully.

Balance billing and excess charges

Balance billing is the difference between what a provider charges and what Medicare allows. CMS defines it as the beneficiary’s responsibility on unassigned claims, capped at 115% of the fee schedule amount for non-participating physicians.

Using the same $200 approved amount, an unassigned claim could look like this:

Item Amount Approved amount $200 Limiting charge (115%) $230 Medicare pays 80% of $200 $160 You owe $70 ($40 coinsurance plus $30 excess)

You might also have to pay the full $230 at the time of service and wait for Medicare to reimburse its share, according to Medicare. The provider should still file the claim. If you do need to file one yourself, see our walkthrough on how to file a Medicare claim.

More on how these fees show up on a bill is in our piece on Medicare excess charges. Some Medigap plans cover excess charges, so that’s worth checking when you compare plans.

How to check before you book

Medicare’s guidance for Original Medicare members is simple: ask before you get services whether the provider charges the Medicare-approved amount. A quick routine:

1. Call the office and ask, “Do you accept Medicare assignment on all claims?”
2. Ask if the practice is participating, non-participating, or opted out.
3. If the answer is non-participating, ask whether they’ll accept assignment for your visit.
4. Ask whether they bill Medicare directly or expect payment up front.
5. For labs, imaging, and equipment suppliers, ask the same questions. They have assignment rules too.

Note the answer and the date. If a bill later exceeds the limiting charge, that record helps when you call Medicare at 1-800-MEDICARE or your supplier’s customer service.

Pathology and lab work is a place where billing codes and Medicare coverage rules matter. A Medicare guide to lab billing codes shows how providers document tests, which helps when you’re comparing what a participating provider will bill.

Does assignment apply to Medicare Advantage?

No, not in the same way. Assignment is a feature of Original Medicare. In a Medicare Advantage plan, you use the plan’s network and cost-sharing rules instead. A provider’s Medicare participation status doesn’t decide what you pay there. Network status and copays do. Our comparison of Part B and Part C lays out the differences, and our page on Medicare Advantage versus Medigap helps you weigh the two paths.

Our perspective

Assignment is one of those Medicare rules nobody explains until a bill arrives. In our work with Colorado clients, the pattern is the same: people choose a plan, then learn which doctors take it, and the order should be reversed.

We’re independent brokers who compare plans across multiple carriers, so we start with your doctors, your prescriptions, and your budget. If you want the predictability of Original Medicare, a Medigap plan such as Plan G or Plan N can be matched to the way you use care. If you prefer a network plan, we’ll review how your providers fit into it.

We also stay with you after enrollment: claims questions, appeals, and an annual review each fall. A confusing bill is exactly the kind of thing we want you to bring us.

Zach

Get help matching your plan to your doctors

If you’re turning 65 or reviewing coverage in Colorado, we can help you compare Medicare Supplement, Medicare Advantage, and Part D options across carriers, at no direct cost to you. Our Medigap plans page is a good place to start, or see all our services.

Prefer to talk it through? Start at Simply Insurance and tell us which doctors you see.

FAQ

What happens if my doctor doesn’t accept Medicare assignment?

They can charge more than the Medicare-approved amount, though for most Part B services no more than 15% above it if they’re non-participating. You might have to pay the whole bill at the visit, and the provider should still submit the claim to Medicare. If the provider has opted out, Medicare won’t pay for non-emergency care.

What’s the difference between Medicare and Medicare assignment?

Medicare is the insurance program. Assignment is a provider’s agreement to accept Medicare’s approved amount as full payment. A provider can see Medicare patients and still not accept assignment on a claim.

Is a participating provider always cheaper for me?

For covered services, a participating provider can’t bill you above the approved amount, so you pay only the deductible and coinsurance. A non-participating provider who accepts assignment on your claim gives you the same result. One who doesn’t may add an excess charge.

Do I need to worry about assignment with a Medicare Advantage plan?

Assignment is an Original Medicare concept. With Medicare Advantage, your costs depend on the plan’s network and copays, so check that your providers are in-network before you enroll.

Sources

• Your Medicare Benefits (Medicare.gov)
• What Is Medicare Assignment and How Does It Affect You? (AARP)
• Does your provider accept Medicare as full payment? (Medicare.gov)
• Annual Medicare Participation (CMS)
• Medicare participation options for physicians (AAFP)
• Medicare assignment explained (Illinois Legal Aid Online)
• CPS Glossary (CMS)
• How to get Medicare services (Medicare.gov)
• Medicare guide to lab billing codes (EIV Diagnostics)

Recommended

• Medicare Excess Charges: Check Assignment Before a $45 Fee
• Avoid Recovery Letters: Medicare Coordination for U.S. Seniors, CO Help
• Medicare Prior Authorization: What It Is and How to Get It