Medicare (Original Medicare): Timely Filing, Appeals, and Billing Guide
Medicare is the federal health program for people 65+ and certain disabled individuals, administered by CMS. Original Medicare (Part A hospital, Part B professional) is billed through regional Medicare Administrative Contractors. Claims must be filed within 12 months of the date of service (42 CFR 424.44), and the first-level redetermination appeal is due within 120 days of the remittance.
- Type
- Federal FFS (Part A/B) via MACs
- Timely filing
- 12 months from DOS (42 CFR 424.44)
- Appeal deadline
- Redetermination: 120 days from RA
- Portal
- MAC portal + Medicare.gov
What is Medicare?
Medicare is the federal health-insurance program run by CMS for people age 65 and older, plus younger people with certain disabilities or ESRD. Original Medicare has two parts you bill: Part A (inpatient hospital, SNF, hospice, home health) and Part B (physician services, outpatient, DME). You submit these to a regional Medicare Administrative Contractor (MAC) — Novitas, Palmetto GBA, NGS, and others — that processes claims for its jurisdiction.
Part C (Medicare Advantage) and Part D (drugs) are private plans; those are billed to the plan, not the MAC. This card covers Original Medicare fee-for-service.
What are Medicare\'s timely filing and appeal deadlines?
Filing is a hard statutory 12 months from the date of service under 42 CFR 424.44 — no contract override, only narrow error-based exceptions. The first appeal, redetermination, is due within 120 days of the remittance date.
| Action | Deadline | Authority |
|---|---|---|
| File claim | 12 months from DOS | 42 CFR 424.44 |
| Redetermination (Level 1) | 120 days from RA | CMS |
| Reconsideration (Level 2) | 180 days from Level 1 | CMS |
What are the five Medicare appeal levels?
- Redetermination — MAC reviews the claim; 120 days to file, decision within 60 days.
- Reconsideration — Qualified Independent Contractor; 180 days to file.
- ALJ hearing — Office of Medicare Hearings and Appeals; 60 days, with a minimum amount in controversy ($200 for 2026).
- Medicare Appeals Council — 60 days from the ALJ decision.
- Federal district court — 60 days from the Council decision, higher dollar threshold.
Most disputes resolve at Level 1 or 2 when the record supports medical necessity. The appeal letter generator has a redetermination template.
What billing quirks should you watch?
- Statutory filing. The 12-month limit is federal and cannot be waived by contract.
- MAC jurisdiction. Bill the correct MAC for the service location; wrong jurisdiction rejects.
- Enrollment required. You must have active Medicare provider enrollment before billing.
- Coverage lives in LCDs/NCDs. Diagnosis-to-service matching drives medical-necessity denials.
Frequently asked questions
Medicare fee-for-service claims must be received within 12 months (one calendar year) of the date of service, set by 42 CFR 424.44. This is a hard federal deadline with only narrow exceptions (such as administrative error by CMS or a MAC). Unlike commercial contracts, it does not vary by provider agreement — it is statutory and applies to all Part A and Part B claims.
Original Medicare has five levels. Level 1 is redetermination by the MAC, due within 120 days of the remittance date. Level 2 is reconsideration by a Qualified Independent Contractor. Level 3 is an Administrative Law Judge hearing (with a minimum amount-in-controversy, $200 for 2026). Level 4 is the Medicare Appeals Council, and Level 5 is federal district court.
Original Medicare (Parts A and B) is billed directly to a regional MAC under federal rules. Medicare Advantage (Part C) is a private plan — such as UnitedHealthcare or Humana — that replaces Original Medicare; you bill the MA plan, follow its prior-authorization and appeal rules, and it must cover at least what Original Medicare covers.
Sources & further reading
Reviewed by the ImmediCare Solutions RCM team
Certified billers and coders handling claims across 50+ specialties nationwide. This entry is reviewed against current payer policy and CMS rules. Last review: Jul 5, 2026.
Stop losing revenue to problems like this.
A free billing audit shows exactly where your practice is leaking money — no cost, no commitment.
