The Medicare 60-day overpayment rule: when the clock starts and how to refund

What does the Medicare 60-day overpayment rule require?

Report and return any Medicare overpayment you’ve identified by the later of 60 days after you identified it or the date a corresponding cost report is due¹. That’s 42 CFR 401.305(b)(1), and it applies to any provider or supplier holding Medicare funds it isn’t entitled to after reconciliation¹.

The teeth are in paragraph (e): an overpayment retained after that deadline is an obligation for purposes of 31 U.S.C. 3729, the False Claims Act¹. So a billing error that was innocent on the day it happened becomes something else on day 61 if you knew and sat on it. That’s why this rule belongs to the billing office, not only to compliance.

And it isn’t about payer demands: a MAC that finds its own error sends a demand letter and recoups on its own timetable². The 60-day rule covers the money you find.

When is an overpayment “identified” under the current regulation?

Under the current regulation, an overpayment is identified when you knowingly receive or retain it, with knowingly taken from the False Claims Act definition, rather than on the day a payer first flags it. The 2025 edition, as amended in December 2024, says a person has identified an overpayment when the person knowingly receives or retains an overpayment, borrowing the meaning of knowingly from 31 U.S.C. 3729(b)(1)(A)¹. The question is what you knew, not when a payer told you; ask your compliance adviser how that standard fits your review process.

In billing terms, a credit balance is a flag, not yet an identification. Identification is the day your review confirms Medicare paid money it shouldn’t have and you can say roughly how much. Log that date.

How does the 180-day investigation pause work?

The deadline is suspended while you run a timely, good-faith investigation into related overpayments, for at most 180 days from the first identification. Paragraph (b)(3) applies when you’ve identified an overpayment but haven’t completed a good-faith investigation into related overpayments from the same or similar cause, and you’re conducting it in a timely way¹. The suspension ends on the earlier of the day the investigation concludes and the aggregate is calculated, or the date 180 days after the initial identification¹.

Two conditions, both yours to prove: timely and good faith. An investigation that opens on day 1 and does nothing until day 150 isn’t timely; one that looks only at the claims you already found, not the pattern behind them, isn’t a good-faith search. Document both as you go.

And the lookback: an overpayment must be reported and returned if you identify it within six years of the date it was received¹, so the search for related overpayments reaches back six years.

How does a credit balance on your A/R become an overpayment?

When posting shows Medicare paid more than it should have and nobody has a reason it’s right. Most credit balances begin on the 835: a duplicate payment posts against a claim already at zero, a patient pays a deductible Medicare then also covers, or a corrected claim processes and the original payment is never taken back.

Posting from the 835 rather than the check is what makes them visible. A Medicare remittance must balance at the service, claim and provider levels, and provider-level adjustments carry PLB reason codes⁴; that’s where a MAC’s recoupment or your own refund appears later. How to read an ERA walks the segments.

Remark codes help you sort the cause. X12 describes RARCs as additional explanation for an adjustment already described by a CARC, or as information about remittance processing, with the informational type prefaced “Alert:”³. A duplicate denial such as CO-18 on a later claim is often the first hint that an earlier one paid twice.

But not every credit is an overpayment: some are posting errors, unapplied patient payments or contractual adjustments taken twice. Work the credit balance report weekly and classify each line.

Which refund route applies: voluntary refund, claim adjustment or a MAC demand?

The one your MAC sets out, chosen by who found the error and how many claims it touches. The regulation says you report and return using an applicable claims adjustment, credit balance, self-reported refund, or other reporting process set forth by the Medicare contractor, and you describe the methodology if you used statistical sampling¹.

The last row is the contractor’s process, not the 60-day rule. A MAC, RAC, SMRC or CERT post-payment records request gives you 45 calendar days to respond, a UPIC request 30, and where a UPIC finds an overpayment the MAC sends the demand letter and collects². Appeal rights run through Medicare Part B appeal levels and deadlines.

How do you document the review so the dates hold up?

With a log that records when you knew what, who decided it, and what you did next. Every date in the regulation hangs on identification and on the investigation being timely and in good faith¹.

Minimum entries: when the credit or finding first appeared; when your review confirmed an overpayment, and the amount; when the investigation opened, who ran it, and the six-year scope¹; interim entries showing it kept moving; the conclusion date and aggregate; the refund route, submission date and MAC acknowledgement; and the PLB or deposit entry showing the money left⁴.

A medical billing audit that samples paid claims against the record finds these before a contractor does, and a payment posting routine that works the credit balance weekly keeps the list short. The recoupment glossary entry covers the vocabulary; the billing KPIs guide shows how unresolved credits distort net collection rate.

What to do this week

• Pull the Medicare credit balance report and classify every line: posting error, unapplied patient payment, or possible overpayment with a date.
• Add an identification date and a suspension-start date to your refund log¹.
• Confirm your MAC’s self-reported refund process and form, and save the link where the posting team can find it¹.
• Ask your biller to read the PLB on every Medicare 835, not just the claim lines⁴.
• Schedule a sample audit of paid claims against documentation; the audit date is the cleanest identification date you’ll have.