|Bill Audit Guide

Select your surgery to filter relevant tips and questions.

Bill Audit Guide — Knee Replacement

How to verify your Medicare bill, understand your rights, and appeal a denial.

Pre-Surgery Billing Checklist

Get an Advance Beneficiary Notice (ABN) if your provider says Medicare might not cover a service

Without an ABN, you may be billed for services Medicare denies. An ABN is your legal notice that you'll be responsible for the cost.

Confirm your hospital admission status: Inpatient vs. Observation

Observation status is billed under Part B (outpatient), not Part A (inpatient). This affects your SNF eligibility and cost-sharing significantly.

Verify all providers accept Medicare assignment

Non-participating providers can charge up to 15% above the Medicare-approved amount (the 'limiting charge'). This extra cost is not covered by Medicare.

Request an itemized estimate of expected charges

Hospitals are required to provide a 'Good Faith Estimate' under the No Surprises Act. This helps you identify unexpected charges before they appear on your bill.

Confirm your Medigap or supplemental plan covers the procedure

Medigap plans vary. Some cover Part A deductibles, some cover Part B coinsurance. Know your plan's benefits before surgery.

After Surgery: Bill Verification Steps

1

Request an itemized bill (not just the summary statement)

Summary bills often hide individual charges. An itemized bill lists every service, supply, and medication with its charge code.

2

Compare your bill to your Medicare Summary Notice (MSN)

Your MSN shows what Medicare was billed, what Medicare approved, and what you owe. Discrepancies between your bill and MSN are red flags.

3

Check for duplicate charges (same service billed twice)

Duplicate billing is one of the most common billing errors. Look for the same CPT code appearing multiple times on the same date.

4

Verify the date of service matches your actual procedure date

Billing for services on dates you were not in the hospital is a billing error (or fraud). Check every line item.

5

Confirm facility fee matches your setting (inpatient vs. outpatient)

Inpatient stays are billed under Part A (DRG payment). Outpatient procedures are billed under Part B (APC payment). The wrong setting code means you're billed incorrectly.

6

Check that your anesthesiologist billed the correct CPT code

Anesthesia CPT codes are procedure-specific. A wrong code means you may be charged more than the Medicare-approved amount for your actual surgery.

Need to Look Up a Specific CPT Code?

Use our CPT Code Audit Guide to look up any code from your hospital bill, see the Medicare-approved amount, and learn what billing errors to watch for.

Medigap Coverage Comparison

Medigap (Medicare Supplement) plans cover some or all of your cost-sharing. Here's how the most common plans compare:

PlanPart A DeductiblePart B CoinsurancePart B DeductibleLimiting ChargeSNF Coinsurance
Plan GCoveredCoveredNot coveredCoveredCovered
Plan NCoveredCovered (copay up to $20)Not coveredNot coveredCovered
Plan F (pre-2020)CoveredCoveredCoveredCoveredCovered

Note: Plan F is only available to those who became eligible for Medicare before January 1, 2020.

Medicare Appeal Rights — 5 Levels

If Medicare denies a claim or you disagree with a coverage decision, you have the right to appeal. There are 5 levels of appeal, each with its own deadline and process.

Free Help Available

SHIP (State Health Insurance Assistance Program) counselors provide free, unbiased help with Medicare billing questions and appeals. Find your local counselor at shiphelp.org