Two ways a payer says no, and the reply to each
Correct or appeal a denied claim. Appeal an Original Medicare demand letter by Day 30 to keep recoupment from starting. Day 1 is the letter's date.
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Your remittance shows a denial: the payer pays nothing on a claim line and gives a reason code. Your payer's demand letter asks for money back on a paid claim, and recoupment takes that money from your later payments.
The replies come from Medicare's overpayment fact sheet and reopening rule, and from UnitedHealthcare's 2026 guide. Match what your payer sent to its row before you reply.
A denial
- Read the reason code. The code names the problem, such as a missing number or a diagnosis the payer won't accept for the service you billed. Your reply depends on whose problem it is.
- Correct the claim, or appeal the denial. UnitedHealthcare's 2026 guide asks for a corrected claim with the number of the claim it replaces. For Original Medicare, ask for a reopening to fix a clerical error, such as a data entry mistake. Appeal a denial you believe is wrong. Your first appeal to Original Medicare is a redetermination.
An Original Medicare demand letter
- Count from the letter's date. Day 1 is the date on the letter, not the day you open it. For claims Medicare denied after paying them, ask for a redetermination by Day 30, and recoupment won't start on Day 41. The letter says what an appeal does to recoupment. Day 120 is your last day to appeal.
- Check the sample. Extrapolation projects the overpayment in a sample of your claims onto every claim under review. Medicare's Program Integrity Manual has an extrapolated demand letter list the sample size, the period, and each sampled claim's overpayment. Check the period and each claim's overpayment against your claims and remittances. Appeal any figure that doesn't match.
Days come from Medicare's overpayment fact sheet, MLN006379, July 2025, for claims Medicare denied after paying them. An appeal filed after Day 30 stops recoupment only once Medicare validates it, and money already recouped stays with Medicare until the decision.
Original Medicare's deadlines don't apply to a commercial insurer's demand, so ask your state's insurance department whether state law limits that demand. Under the Employee Retirement Income Security Act (ERISA), a for-profit company's self-funded plan isn't treated as an insurer under state insurance law, so read your network contract.
JotPsych shows a denied claim's reason in the payer's words, a plain reading, and the actions the claim allows next.
Book 15 minutes- Centers for Medicare & Medicaid Services (CMS), Medicare Overpayments, MLN006379, July 2025: Demand Letter, Other Options (appeal), and Overpayment Debt Collection Activities; read October 4, 2026.
- 42 CFR 405.379, Medicare overpayment recoupment limitation, paragraphs (b) and (d); read October 4, 2026.
- 42 CFR 405.980, reopening of initial determinations: paragraph (a)(3), clerical errors; read October 4, 2026.
- CMS, Medicare Program Integrity Manual, Chapter 8, sections 8.4.1.2 and 8.4.7.1: statistical sampling and what the demand letter describes; read October 2, 2026.
- UnitedHealthcare, 2026 Care Provider Administrative Guide, effective April 1, 2026: Chapter 10, corrected (replacement) claim submissions.
- National Association of Insurance Commissioners, Insurance Departments, the directory of state insurance departments; read October 3, 2026.
- 29 U.S.C. 1144, ERISA section 514(b)(2)(B); read October 2, 2026.