What Medicare Part A Covers for Outpatient Surgery

Medicare Part A covers inpatient hospital surgery, not outpatient surgery at a surgery center or doctor's office

Medicare Part A pays for surgery when you are admitted to a hospital as an inpatient — meaning you stay overnight or longer. It does not pay for outpatient surgery, which is surgery performed at an ambulatory surgery center, a hospital outpatient department, or a doctor's office where you go home the same day. If your surgery is scheduled as outpatient, Part A will not cover the facility costs, the surgeon's fee, or the anesthesia.

The distinction matters because hospitals often perform the same surgery both ways. Your doctor might schedule you as an inpatient or outpatient depending on your health, the complexity of the procedure, and the hospital's capacity. The coverage you receive depends entirely on how the hospital classifies your admission — not on the type of surgery itself.

Key Takeaways

Medicare Part A covers the facility costs of inpatient surgery (surgery requiring an overnight hospital stay), but not outpatient surgery performed at a surgery center or hospital outpatient department.
Outpatient surgery is covered under Medicare Part B, which pays 80 percent of the surgeon's fee and facility costs after you meet your annual deductible.
If you have a Medigap or Medicare Advantage plan, your coverage for outpatient surgery may differ from Original Medicare, so check your plan documents.
The hospital decides whether to admit you as inpatient or outpatient based on your condition and medical necessity, not your preference.

How Medicare Part A and Part B divide outpatient surgery costs

When you have outpatient surgery, Medicare Part B — not Part A — covers the costs. Part B pays 80 percent of the approved amount for the surgeon's fee, the facility fee, and anesthesia after you have met your annual Part B deductible (which is $240 in 2024, though this amount changes yearly). You pay the remaining 20 percent as coinsurance, plus any amount above the approved rate if your surgeon does not accept Medicare assignment.

Part A does not contribute to outpatient surgery costs at all. Its hospital insurance benefit is designed for inpatient stays, where it covers room, board, nursing care, and most hospital services for up to 60 days in a benefit period. Once you leave the hospital the same day, Part A's coverage ends.

If you have Original Medicare (Part A and Part B together), you are responsible for the 20 percent coinsurance on outpatient surgery unless you have a Medigap policy or Medicare Advantage plan that covers it.

When the hospital admits you as inpatient versus outpatient

Your surgeon does not decide whether you are admitted as inpatient or outpatient — the hospital does, based on medical necessity and a federal guideline called the Inpatient-Only List. Some surgeries are always inpatient (such as open-heart surgery or major joint replacement). Others can be done either way depending on your age, other health conditions, and how complex your case is.

If your surgery is on the Inpatient-Only List, the hospital must admit you as an inpatient and Part A will cover it. If your surgery is not on that list, the hospital may choose outpatient, and Part B will cover it instead. You can ask your surgeon and the hospital's admissions department which classification they are planning, but you cannot override their decision based on which insurance covers it better.

The hospital's choice affects your out-of-pocket cost significantly. Inpatient surgery under Part A requires you to pay a deductible (currently $1,632 per benefit period in 2024) but then covers most costs. Outpatient surgery under Part B requires a separate deductible and leaves you paying 20 percent of all costs.

What you pay out of pocket for outpatient surgery under Part B

Your costs depend on whether you have met your Part B deductible for the year. If you have not, you pay the full deductible first ($240 in 2024), then 20 percent of the approved amount for the surgery itself. If you have already met your deductible earlier in the year, you pay only the 20 percent coinsurance.

The approved amount is set by Medicare, not by what the surgeon charges. If your surgeon accepts Medicare assignment, they agree to accept the approved amount as full payment (except for your coinsurance). If they do not accept assignment, you may owe the difference between their charge and the approved amount on top of your coinsurance.

Ask your surgeon's office and the surgery facility in advance whether they accept Medicare assignment. This single question can save you hundreds of dollars.

Outpatient surgery coverage under Medicare Advantage and Medigap

If you have a Medicare Advantage plan (Part C), your coverage for outpatient surgery is determined by your plan, not by Part A or Part B rules. Most Medicare Advantage plans cover outpatient surgery, but the deductible, coinsurance, and copay amounts vary widely by plan. Some plans cover 100 percent after a copay; others require coinsurance similar to Original Medicare. Check your plan's summary of coverage or call the plan directly before your surgery.

If you have Original Medicare plus a Medigap policy, the Medigap plan may cover some or all of the 20 percent coinsurance you would otherwise pay for outpatient surgery. Plans C, D, F, G, M, and N all cover at least part of the Part B coinsurance. Plans A and B do not. Review your Medigap policy documents or call your insurer to confirm what your plan covers for outpatient surgery.

How to find out what your outpatient surgery will cost

Before your surgery, contact the surgery facility's billing department and ask for an estimate based on the specific procedure code your surgeon plans to use. Ask them to tell you the Medicare-approved amount, not the surgeon's full charge. Then calculate: approved amount minus any deductible you still owe, times 20 percent, plus any coinsurance your Medigap or Medicare Advantage plan does not cover.

You can also search the Medicare Physician Fee Schedule on the Centers for Medicare and Medicaid Services website to find the approved amount yourself, though the facility's billing department can usually do this faster. Getting this number in writing before surgery prevents surprises in the mail weeks later.

If the estimated cost is higher than you expected, ask your surgeon whether the procedure can be done in a less expensive setting or whether there are less costly alternatives. Some surgeries can be done in a doctor's office rather than a surgery center, which may lower the facility fee.

What happens if you are admitted as inpatient after planning outpatient surgery

Occasionally a surgeon discovers during an outpatient procedure that you need to stay overnight in the hospital. When this happens, the hospital can reclassify you as an inpatient, and Part A takes over coverage from that point forward. You will owe the Part A deductible for the hospital stay, but Part A will then cover most of your inpatient costs.

If you are reclassified from outpatient to inpatient, the facility should notify you and explain how your coverage changes. If you receive a bill for the outpatient portion before the reclassification is processed, contact the billing department and ask them to resubmit the claim under Part A inpatient rules.

Frequently Asked Questions

Does Medicare Part A cover cataract surgery?

Cataract surgery is almost always performed as outpatient surgery, so Part B covers it, not Part A. You pay the Part B deductible (if you have not met it) plus 20 percent coinsurance. If you have Medigap or Medicare Advantage, your plan may cover some or all of the coinsurance.

What if my doctor says I need surgery but I am not sure if it will be inpatient or outpatient?

Ask your surgeon's office to contact the hospital and find out the planned admission status. Once you know, you can call your insurance (Medicare, Medigap, or Medicare Advantage) and ask what your out-of-pocket cost will be. Getting this answer before surgery lets you plan financially and avoid bill surprises.

Can I choose to be admitted as inpatient instead of outpatient to save money?

No. The hospital makes this decision based on medical necessity and federal guidelines, not on your preference or insurance coverage. You cannot request inpatient status to reduce your coinsurance, and the hospital cannot admit you as inpatient if your condition does not medically require it.

If I have a Medigap plan, do I still pay 20 percent for outpatient surgery?

It depends on your Medigap plan. Plans C, D, F, G, M, and N cover at least part of the Part B coinsurance. Plans A and B do not. Check your policy documents or call your Medigap insurer to see what percentage they cover for outpatient surgery.

What if the surgery center bills me more than Medicare's approved amount?

If the facility accepts Medicare assignment, they cannot bill you more than the approved amount plus your coinsurance. If they do not accept assignment, you may owe the difference. Always ask in advance whether the facility accepts Medicare assignment for your procedure.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.