What Medicare patients pay for an outpatient procedure

People on Medicare are often told that Part B pays 80 percent and they pay 20, and then they get a hospital statement that does not look like 20 percent of anything they recognize. The reason is structural. A hospital outpatient procedure creates at least two claims, each paid under a different Medicare system, and each carries its own share for you. This guide lines the two shares up for five procedure codes that have price pages on this site, using the CY2026 Medicare files checked on October 22, 2026, and states every assumption behind the arithmetic.

Two limits up front. The figures are Medicare anchors: the professional fee amounts are for Michigan Locality 01, and the hospital amounts are national unadjusted rates before the wage-index adjustment that applies to a real claim. They describe how the shares are built, not what your bill will say. And the examples cover Original Medicare only. A Medicare Advantage plan, an employer retiree plan or a Medigap policy changes who pays the shares below.

Why one procedure creates two cost shares

Medicare.gov states the rule for hospital outpatient services in two sentences. You pay about 20 percent of the Medicare-approved amount for doctor and other provider services, and you also pay a separate copayment to the hospital for each service you get in a hospital outpatient setting, except for certain preventive services. That copayment is usually no more than the Part A inpatient hospital deductible, which is $1,736 in 2026.

Behind those sentences are two payment systems. The doctor, or the physician group, is paid under the physician fee schedule, so the amount Medicare approves for the doctor's work is a fee schedule amount for the facility setting. The hospital is paid under the outpatient prospective payment system, which assigns the hospital's service to an ambulatory payment classification, or APC, and pays a fixed rate for it. The site's comparison of hospital outpatient departments and imaging centers explains why the same CPT code can be paid under either system depending on where it is done. Here the setting is the hospital outpatient department, so both claims exist.

You pay the Part B deductible first in any calendar year. In 2026 it is $283, according to the CMS fact sheet and Medicare.gov, and it is paid once. After you meet it, the 20 percent coinsurance applies to Part B-covered services when the provider accepts assignment. Everything in the tables below assumes the deductible has already been met earlier in the year, and says so. Whether the deductible has been met is a fact only your own Medicare statements can confirm.

The anchors for five codes, one layer at a time

The table keeps the two layers apart. The left side is the Medicare-approved amount for the professional fee, the right side is the hospital's APC payment and the minimum unadjusted copayment CMS lists for it. Nothing in the table adds the layers together.

Sources: CMS Physician Fee Schedule relative value file RVU26D (October 2026 release) with 2026 geographic practice cost indices, $33.4009 conversion factor; CMS OPPS October 2026 Addendum B (updated October 14, 2026), payment rate and minimum unadjusted copayment columns. Checked October 22, 2026. The national unadjusted copayment column in Addendum B is blank for these codes, so the minimum unadjusted copayment is shown.

A note on the status indicators. Codes 66984, 64721 and 29881 carry indicator J1, which marks a comprehensive APC: the hospital receives one payment for the primary procedure, and most related services on the same claim are packaged into it. That is why the table shows the APC payment as the hospital layer rather than a list of line items. Code 70551 carries Q3, and its APC amount applies when the scan is billed alone, not as part of a multi-scan combination. Code 45378 carries T, a separately paid procedure APC. CMS defines each indicator in its OPPS addenda, and the hospital's own claim determines which payment actually applies.

Your share, with the deductible already met

The second table converts the anchors into the two cost shares. The professional share is 20 percent of the Medicare-approved amount, rounded to the cent. The hospital share is the minimum unadjusted copayment from Addendum B. The last column is only the sum of those two shares, which this guide computes for illustration. No Medicare file publishes it, it leaves out anesthesia, pathology, supplies billed by other parties and anything the hospital's claim adds, and it is not a price.

Computed by MyCarePrice from the table above. Assumes the Part B deductible is already met, the provider accepts assignment, and a diagnostic (not screening) service. National unadjusted hospital rates; Michigan Locality 01 professional rates.

Two patterns are worth seeing, because they are not obvious from the Medicare rule alone.

• For the surgical codes, the hospital copayment is the larger share. For the knee arthroscopy code, the professional share is $107.88 and the hospital copayment is $668.58, about 6 times as much. The surgeon's fee schedule amount is a fraction of the comprehensive APC payment, so 20 percent of each differs by the same ratio. Someone who budgets only for 20 percent of the surgeon's fee will be well short.
• For the imaging code, the hospital copayment is again larger than the professional share, but both are small. The professional layer for the brain MRI is the interpretation, the professional component with modifier 26, at $69.04, and the hospital's technical side is paid through APC 5523. The two shares are $13.81 and $48.76.

None of the five copayments comes close to the $1,736 cap that Medicare.gov describes. The highest is $668.58. The cap matters for much more expensive hospital services; for these procedures it never binds, so the cap does not change the arithmetic in the table.

Reading each code, one at a time

Diagnostic colonoscopy, 45378

The table treats 45378 as a diagnostic service, which is how its name reads. Medicare treats screening colonoscopy differently, and Medicare.gov says the difference is large. For screening, you pay nothing if your provider accepts assignment. If a polyp or other tissue is removed during the screening, Medicare.gov says you pay 15 percent of the Medicare-approved amount for the provider's services, and in a hospital outpatient department or ambulatory surgery center you also pay the facility a 15 percent coinsurance, and the Part B deductible does not apply. That 15 percent is not the same as the 20 percent in the table. It is a separate rule, and which rule applies to a colonoscopy is determined by how the service is billed, which the order and the claim decide. The question to ask in advance is whether the service is expected to be billed as screening or as diagnostic, and what the cost share would be if the plan changes mid-procedure. The colonoscopy price page shows the 45378 anchors in full.

Brain MRI without contrast, 70551

The professional share on a 70551 claim in a hospital is small because only the reading is billed by the physician, at $69.04. The hospital copayment $48.76 covers the scan itself. If the same scan were done in a freestanding imaging center, one global amount of $192.65 would apply under the fee schedule and the 20 percent would be taken from that single figure, as the MRI price page explains. That comparison, setting against setting, is one of the biggest levers on a Medicare patient's share, and it is covered in the guide on hospital outpatient departments and imaging centers.

Cataract surgery with lens implant, 66984

The professional share is $93.56 and the hospital copayment is $471.57. A separate Medicare rule affects what comes after: Medicare.gov says that after cataract surgery with an intraocular lens, Medicare covers one pair of eyeglasses with standard frames or one set of contact lenses, with 20 percent coinsurance after the Part B deductible, and the supplier must participate in Medicare. That is a different claim with its own share. The cataract surgery price page has the details.

Carpal tunnel release, 64721

The share is $87.58 to the surgeon's layer and $399.01 to the hospital layer. This code also has a nonfacility fee schedule amount for office-based work, so the professional layer can differ if the setting is not a hospital outpatient department. Ask where the procedure will happen before you compare any figure. See the carpal tunnel release page.

Knee arthroscopy with meniscectomy, 29881

The largest hospital copayment of the five, $668.58, comes with a professional share of $107.88. The hospital layer is a comprehensive APC payment of $3,342.87, with most related hospital services packaged in. Anesthesia is billed separately by the anesthesia practice, and its own Medicare arithmetic is worked through in the anesthesia bill guide. See the knee arthroscopy page for the surgeon and hospital anchors. CMS lists knee arthroscopy for knee osteoarthritis among the services in a prior authorization model for Original Medicare that began in six states in 2026; check whether your code is on the current list, as described in the guide on prior authorization before a procedure.

What moves your actual share away from the table

The Part B deductible is not met

The deductible is paid once a year before Original Medicare starts to pay. If you have $283 still to meet, the first approved amounts in the year count toward it, and your share of those claims is the full approved amount, not 20 percent. For example, if the professional amount of $172.49 for 45378 were the first claim of the year, the whole amount would count toward the $283 deductible and the beneficiary would owe all of it, with $110.51 of the deductible left for the next claim. How a deductible balance interacts with a hospital outpatient claim and its copayment is shown on the Medicare Summary Notice, and this guide does not compute it, because the rule depends on how the claims are processed and in what order.

The provider does not accept assignment

Medicare.gov says a non-participating provider may charge more than the Medicare-approved amount, up to a limiting charge of 15 percent above it for most services. The CMS documentation for the relative value file gives the arithmetic: the limiting charge is 115 percent of the payment amount for a nonparticipating physician, which is set at 95 percent of the fee schedule amount, so the factor is 1.0925. For the professional amount of $172.49 for 45378, the limiting charge is $188.45. Hospital copayments are not affected. Ask any physician whether they accept assignment before you book.

Supplemental coverage

Medicare.gov describes a Medigap policy as private insurance that can pay part of the copayments, coinsurance and deductibles under Original Medicare. If you have one, your share of the table above may be partly or wholly covered by the policy. If you have retiree coverage from an employer, the plan's rules apply. Neither changes the Medicare-approved amounts or the hospital payment rate in the tables, only who pays the share.

Medicare Advantage

A Medicare Advantage plan sets its own copayments and coinsurance for outpatient procedures, in its plan documents, and uses its own network and authorization rules. Original Medicare has no yearly out-of-pocket maximum unless you have supplemental coverage; Medicare Advantage plans have their own limits. If you have an Advantage plan, ask it for the cost-sharing for the exact CPT code and facility, as the guide on estimating your cost with insurance describes.

The hospital's wage index

The hospital payment and copayment in this guide are national unadjusted figures. A hospital's actual payment is adjusted for local labor costs, so its copayment will differ from the table. Expect it to be near the table, not equal to it.

Services outside the two claims

Anesthesia, a pathologist's reading of a tissue sample, a separate facility charge for supplies, and any additional procedure on the same day are billed apart from the two claims above. Each carries its own Medicare share. The tables describe the surgeon and the hospital claim for the named code, nothing more.

Which cost-sharing rule applies? A short decision table

Sources: Medicare.gov pages on colonoscopies and mammograms, checked October 22, 2026.

Questions to ask before booking

1. What is the exact CPT code, and is it billed as screening or diagnostic?
2. Is the procedure in a hospital outpatient department, an ambulatory surgery center or an office? The rules above are for the hospital outpatient department.
3. Does the physician accept assignment, and do all other billing physicians, such as anesthesia and pathology?
4. What is the hospital's estimated copayment for this code? Ask for it in writing, and ask whether the number is wage-adjusted.
5. Have I met my Part B deductible this year? Your Medicare statements show the amount.
6. Do I have Medigap, retiree or Medicaid coverage that picks up part of the shares, and does the provider bill it directly?

Answers in writing, with the date and the name of the person, are the record to bring back if the statement differs. For the wording of a call, use the billing questions guide.

After the procedure: matching the statement to the shares

Medicare sends Medicare Summary Notices for Part B claims, and your Medigap or retiree plan may send its own statement. Match each claim to its layer. A professional claim should show an approved amount near the fee schedule figure for the locality and about 20 percent as your share. A hospital claim should show the procedure's APC payment and a copayment near the table's figure, adjusted for wage index. If the amounts differ widely from the anchors, ask the billing office to explain which claim and which rule produced the number. The guide on checking an itemized bill for errors covers duplicates and services you did not receive, and the one on the Advance Beneficiary Notice covers the case where a provider says Medicare may not pay.

Medicare outpatient costs: reader questions

Sources and check dates

• Medicare.gov, Costs: Part B deductible $283, 20 percent coinsurance, hospital outpatient copayment rule. Checked October 22, 2026.
• CMS, 2026 Medicare Parts A and B premiums and deductibles: Part A inpatient deductible $1,736, Part B deductible $283. Checked October 22, 2026.
• CMS, OPPS quarterly addenda, October 2026 Addendum B: payment rate, status indicator, APC and minimum unadjusted copayment for 45378, 70551, 66984, 64721 and 29881. Checked October 22, 2026.
• CMS, Physician fee schedule relative value file RVU26D and 2026 geographic practice cost indices (Michigan Locality 01), including the limiting-charge factor of 1.0925. Checked October 22, 2026.
• Medicare.gov, Colonoscopies, Mammograms, Eyeglasses and contact lenses, Does your provider accept Medicare as full payment and Medigap. Checked October 22, 2026.

Prices only. No diagnosis or treatment advice. Medicare anchors are not your bill. The shares shown are arithmetic on those anchors under stated assumptions. Confirm your price in writing before service.

If you are choosing between a hospital and a freestanding site for the same code, the next useful step is the side-by-side of the two payment systems, because the setting often moves a Medicare patient's share more than anything else on this page.