Medicare Advantage billing: claim denials, appeals and payment

Medicare Advantage filing, prior authorization and portal

Appeal levels

Top denials from Medicare Advantage

Who pays a Medicare Advantage claim?

The plan pays. Under 42 CFR 422.101(a), each Medicare Advantage (MA) organization must cover all Part A and Part B services by furnishing, arranging or paying for them, so you bill the plan named on the member card and not the MAC. Confirm plan enrollment for the date of service before you send a claim.

Many sponsors run several MA products. UnitedHealthcare, Humana and Wellcare each have their own guide, and each plan manual controls portals, payer IDs and contract filing terms. Original Medicare rules are on the Medicare guide.

Medicare Advantage is also called Part C, and an MA plan has to follow Original Medicare coverage rules. Under 42 CFR 422.101(b), the plan must comply with national coverage determinations, the general coverage and benefit conditions of Traditional Medicare, and written local coverage decisions, which includes the inpatient admission payment criteria at 42 CFR 412.3 (the basis of the two-midnight rule). CMS added that language in CMS-4201-F, the Contract Year 2024 final rule published April 12, 2023 (88 FR 22120) and effective June 5, 2023.

What is the Medicare Advantage timely filing limit?

There is no single federal limit for contracted providers. 42 CFR 422.520(b)(1) requires the contract between the plan and the provider to contain a prompt payment provision whose terms both parties agree to, and the plan must pay contracted providers under the terms of that contract. Read your own agreement and the plan manual.

Plans differ in what they write. Humana's Jan. 1, 2026 HMO D-SNP Provider Billing Guide for Illinois says its timely filing requirement for all providers, in and out of network, is 365 days from the date of service. If the member has other coverage, the period starts on the date of payment or notice of nonpayment from the primary payer. Other plans and products can differ, so timely filing limits by payer is the place to compare, and the timely filing calculator returns a date.

There is one federal exception worth knowing. If a member is disenrolled retroactively and the plan recovers its payment from you six months or more after the service, 42 CFR 424.44(b)(4) extends the time to file with Original Medicare through the last day of the sixth calendar month after the recovery.

How fast must a Medicare Advantage plan pay?

For a provider without a contract, 42 CFR 422.520(a) sets two clocks. The plan must pay 95 percent of clean claims within 30 days of receipt for private fee-for-service plans and for services not furnished under a written agreement, with interest on clean claims not paid within 30 days. All other claims from non-contracted providers must be paid or denied within 60 calendar days of the request.

For contracted providers the clock is whatever the contract says. The payment amount for a provider with no contract is set by 42 CFR 422.214. A non-contracted provider other than a section 1861(u) provider of services must accept the amount it could collect if the patient were in Original Medicare. A non-contracted hospital or other section 1861(u) provider must accept the Original Medicare amount, less the indirect and direct medical education payments in 42 CFR 412.105(g) and 413.76. A non-contract section 1861(u) provider that submits the information it would send Original Medicare is deemed to be seeking that rate unless it tells the plan in writing that it is billing less.

This is the rule that matters to ER groups and hospitals that treat a plan's member without a contract. It caps the payment at the Original Medicare amount, so there is no higher rate to negotiate.

How long does the plan have to decide a request?

An organization determination is the plan's decision on whether it will provide or pay for a service, and 42 CFR 422.566(b) lists payment for emergency and urgently needed services, refusal to pay for services in whole or part, and reduction or early end of an authorized course of treatment among them. The enrollee, or any provider that furnishes or intends to furnish services, can request one. A payment request must be in writing, unless the plan accepts verbal ones.

The denial notice must be in writing to the enrollee and the provider involved, state the specific reasons for the denial and explain the right to a reconsideration (42 CFR 422.568(d) and (e)). A partly or fully adverse medical necessity decision on the initial review must be reviewed by a physician or other appropriate health care professional with expertise in the field (42 CFR 422.566(d)).

How does a Medicare Advantage denial get appealed?

Ask the plan for a written reconsideration within 60 calendar days of receiving the denial notice, and the plan sends the case to an independent entity if it keeps its decision. Subpart M of 42 CFR part 422 sets this path, and the later levels borrow the Original Medicare rules in part 405.

What prior authorization rules apply to Medicare Advantage?

A coordinated care plan can use prior authorization only for three purposes under 42 CFR 422.138(b): to confirm diagnoses or other medical criteria that are the basis for coverage, to ensure a basic benefit is medically necessary, or to ensure a supplemental benefit is clinically appropriate. The plan cannot use it for anything else.

An approval has force. Under 422.138(c), if the plan approved a covered item or service through prior authorization, a pre-service determination or a concurrent determination, it may not deny coverage later on medical necessity grounds and may not reopen the decision except for good cause or reliable evidence of fraud or similar fault. Keep the authorization number and date on the claim and in your file, because they are your proof if a medical necessity denial follows.

Two newer rules in 42 CFR 422.122 apply to MA plans. Beginning January 1, 2026, a denial of a prior authorization request must include a specific reason, and beginning in 2026 the plan must post prior authorization metrics each year, including approval and denial percentages and average decision times, with a report due March 31. Beginning January 1, 2027, the plan must maintain a prior authorization API. These rules exclude drugs.

Can I use open negotiation and IDR with a Medicare Advantage plan?

No. The CMS No Surprises Act key protections document, revised June 2026, says the surprise billing protections do not apply to people covered only through Medicare, including Medicare Advantage, or Medicaid, including managed care. For a non-contracted MA claim, 42 CFR 422.214 sets the payment instead. Out-of-network IDR for commercial plans starts at out-of-network billing and IDR.