You call a doctor to book an appointment. They say, "Yes, we take Medicare." That sounds like a green light. But there is a second question that decides how much you actually pay. It is: do they accept Medicare assignment? Here is what that phrase means and why it can save or cost you real money.
The short answer
Medicare assignment is a deal between the doctor and Medicare. When a doctor accepts assignment, they agree to bill only the Medicare-approved amount for a service. You pay just your normal 20% coinsurance (or your Medigap covers it).
When a doctor does NOT accept assignment, they can charge up to 15% more than Medicare pays. You owe that extra amount.
About 96% of doctors accept assignment. Ask before every new provider.
What "Medicare-approved amount" means
Medicare sets a fee schedule for each medical service. That fee is called the Medicare-approved amount. It is different from what the doctor's office might list as their "regular price."
For example, a routine office visit might have:
- Doctor's list price: $180
- Medicare-approved amount: $100
- What Medicare pays: $80 (80% of approved)
- What you owe: $20 (20% of approved)
Notice the doctor's list price does not matter to Medicare. All that matters is the approved amount. But whether the doctor accepts assignment decides how the rest of the bill is handled.
Two Medicare agreements a doctor can make
Doctors who see Medicare patients pick from these arrangements:
Option 1: Participating (accepts assignment on all Medicare claims)
They agree, in writing, to accept the Medicare-approved amount for every service, every time, for every Medicare patient. Medicare pays 80% directly to the doctor. You pay 20%.
Option 2: Non-participating
They are enrolled in Medicare but did NOT agree to accept assignment across the board. They can decide, case by case, whether to accept assignment or not. If they do not, they can bill you up to 15% more than the Medicare-approved rate. See our full article on Medicare Part B excess charges.
Option 3: Opt-out (private contract)
They are not enrolled in Medicare at all. Medicare pays them nothing. You sign a private contract and pay 100% out of pocket. Concierge doctors often do this.
The money side by side
Same office visit. Same Medicare-approved amount ($100). Different provider types:
| Provider type | What Medicare pays | What you pay | Total |
|---|---|---|---|
| Participating (accepts assignment) | $80 | $20 | $100 |
| Non-participating (does not accept) | $76 | $39 | $115 |
| Opt-out (private contract) | $0 | Whatever they charge | Whatever they charge |
The gap between $20 and $39 is not huge on one visit. Multiply it across a year of specialist appointments, imaging, and procedures and it adds up.
Where assignment matters most
Assignment matters more for some services than others.
Routine primary care visits
Almost every primary care doctor accepts assignment. This category is safe.
Specialists
This is where you have to check. Some specialists (surgeons, dermatologists, ophthalmologists) are more likely to be non-participating, especially in private practice.
Hospital care
Hospitals themselves must accept assignment for Part A services. But some doctors who work inside hospitals (radiologists, anesthesiologists) might not. Those show up as surprise bills.
Lab tests and imaging
Standalone labs and imaging centers vary. Big chains usually accept assignment. Some smaller shops do not.
Durable medical equipment
DME suppliers must accept assignment if they are enrolled in Medicare. Suppliers who do not enroll can charge whatever they want.
How to check before you go
Two ways to check any provider's Medicare status:
1. Ask when you call
The one-line script:
"I have Original Medicare. Do you accept Medicare assignment?"
Listen for a clear "yes." Anything vague ("we take Medicare," "we bill Medicare") is not the same. Ask again if you need to.
2. Look it up on Medicare.gov
Use the Medicare.gov Care Compare tool. Search for the provider. The listing shows whether they accept assignment on all Medicare claims. Free, no login, works from any browser.
Assignment and Medicare Advantage
Medicare Advantage plans work under different rules. Assignment does not apply the same way. Advantage plans have their own network and copay structure. You pay the plan's copay for an in-network visit, regardless of what Medicare's approved amount would be.
The concern shifts. Instead of asking "do you accept assignment," you ask "are you in this plan's network?" Out-of-network can cost more than an excess charge. See our Medicare HMO vs PPO guide.
Assignment and Medigap
Medigap (Medicare Supplement) plans work with Original Medicare. The plan pays for services Medicare covers, based on what Medicare approves.
If a doctor accepts assignment: Medicare pays 80%, Medigap pays 20%, you pay $0 (Plan G) or a small copay (Plan N).
If a doctor does NOT accept assignment: Medicare pays about 76%, Medigap Plan G pays your 20% coinsurance AND the excess charge. You pay $0. Plan N pays only your standard 20% coinsurance and NOT the excess.
This is why Plan G is popular for people who want predictable costs. It absorbs the excess-charge risk. Plan N does not.
Assignment on lab work, imaging, and DME
Assignment applies to almost every kind of Medicare Part B service, not just doctor visits. Some categories to check:
Lab tests
Big national labs like Quest and LabCorp accept assignment as a rule. Hospital-based outpatient labs usually accept assignment. Small independent labs vary.
Imaging centers
MRIs, CT scans, and X-rays at freestanding imaging centers can be a mixed bag. Ask before you go. A non-participating imaging center on a $1,200 scan can cost you an extra $180.
Durable medical equipment (DME)
Wheelchairs, walkers, CPAP machines, oxygen. Medicare-enrolled DME suppliers must accept assignment. Non-enrolled suppliers can charge whatever they want. Use only Medicare-enrolled suppliers.
Ambulance services
Most Medicare-approved ambulance services accept assignment. In an emergency you cannot exactly shop, but check follow-up bills carefully.
How assignment plays out over a year
Small differences add up. Consider a typical senior with:
- 4 primary care visits (participating): $80 total
- 3 specialist visits (participating): $60 total
- 1 MRI (participating): $40 total after Medigap
- Yearly total: $180 out of pocket
Now the same year but with a non-participating specialist for the 3 visits:
- 4 primary care visits: $80
- 3 specialist visits (non-participating, 15% excess): $180
- 1 MRI: $40
- Yearly total: $300 out of pocket
$120 extra per year without any real benefit unless the doctor is truly exceptional. This is why cost-conscious seniors ask up front.
What if a doctor bills me more than they should?
If a participating doctor tries to charge you more than Medicare's approved amount, that is a rule violation. Your steps:
- Compare the bill to your Medicare Summary Notice (mailed every 3 months or available in your Medicare.gov account)
- Call the doctor's billing office. Point to the MSN and the approved amount
- If they will not correct it, call 1-800-MEDICARE and file a complaint
- You can also contact your State Health Insurance Assistance Program (SHIP) for free help
Doctors who violate assignment agreements can be dropped from Medicare. Reporting works.
Common mistakes
Assuming every doctor takes assignment because they said "we take Medicare"
Different phrases mean different things. Ask the specific question.
Not checking specialists before referrals
Your primary care doctor might send you to a specialist without checking their Medicare status. Ask before you book.
Skipping the Medicare Summary Notice
The MSN is your receipt for everything Medicare paid. Read it. It shows if a doctor is charging above approved amounts.
Paying the balance the front desk asks for
Some offices try to collect the full billed amount up front. If you are on Medicare, you only owe what Medicare's cost-share is. Do not overpay just because the receptionist asks. Ask them to bill Medicare first.
Signing an "advance beneficiary notice" without reading it
An ABN is a form saying you agree to pay if Medicare denies the service. Read it. If you sign, you might owe the full billed amount, not the approved rate.
Why assignment matters for your yearly cost
The average senior on Original Medicare sees a doctor 8 to 12 times per year, plus tests and imaging. If even one specialist you use every month does not accept assignment, that is $15 to $50 extra each visit.
Over a year, non-assignment costs can add $200 to $800 on top of what you would pay with a full-assignment provider. Plus the doctor visit copays. Plus any hospital or surgical work.
This is why Medicare cost planning starts with knowing your provider's status. See what Medicare really costs in our full 2026 cost guide.
The bottom line
Medicare assignment is a small phrase with a big effect on your bill. Doctors who accept assignment take what Medicare approves and cannot charge you more. Doctors who do not accept can bill up to 15% extra.
Three moves to stay ahead:
- Ask every new provider: "Do you accept Medicare assignment?"
- Look them up on Medicare.gov Care Compare
- Pick a Medigap plan (like Plan G) that covers excess charges if you want zero surprises
Not sure whether Original Medicare, Advantage, or Medigap fits you best? Book a free call. We will walk through your doctors and prescriptions and put real numbers next to each option.
Frequently asked questions
What does it mean when a doctor accepts Medicare assignment?
They agree to accept the Medicare-approved amount as full payment. You only owe your standard 20% coinsurance. About 96% of doctors accept assignment.
What is the difference between accepting Medicare and accepting assignment?
Accepting Medicare means the doctor is enrolled and bills Medicare. Accepting assignment goes further: they agree not to charge you more than Medicare approves. A doctor can accept Medicare but not accept assignment.
Do all doctors accept Medicare assignment?
No. About 96% do. The remaining 4% are non-participating and can charge up to 15% extra. Some doctors opt out of Medicare entirely and require full private payment.
How do I check if a doctor accepts Medicare assignment?
Call and ask directly, or search the provider at Medicare.gov Care Compare. The listing shows their Medicare status.
What happens if my doctor does not accept assignment?
You can still see them. You may owe up to 15% more per service. Medigap Plan G and Plan F cover that excess charge. Plan N does not.