How to appeal a denied Medicare claim (Part A or Part B)

If your parent's Medicare Summary Notice shows "NO" next to a service, the first appeal step is a "redetermination." Here is how the deadline is counted, what to send, and where.

Last checked against the sources below: October 23, 2026.

First: is this Original Medicare or a plan?

The Medicare Summary Notice (MSN) is the notice people with Original Medicare (Part A and Part B) get [7]. If your parent is in a Medicare Advantage Plan or a Part D drug plan, the denial came from the plan and the clock is different: see the box at the end.

How long do I have to appeal a denied Medicare claim?

The rule counts 120 days from the day your parent receives the notice:

"...must be filed within 120 calendar days from the date a party receives the notice of the initial determination." (42 CFR 405.942(a)) [1]

Receipt is presumed 5 days after the notice date, unless there is evidence otherwise [1][4]. In practice that is about 125 days from the date printed on the MSN.
"Filed" means received. The request counts as filed on the date the Medicare contractor receives it, not the day you mail it [1].
Go by the date printed on the notice. The MSN's last page prints a "We must receive your appeal by" date, and Medicare.gov says to file by the date in the MSN [8][6].

Our free appeal deadline tool does the counting. If its answer ever differs from the date printed on your parent's MSN, use the MSN's date.

Is there a minimum dollar amount to appeal?

Not at this first level. The regulation allows a redetermination "regardless of the amount in controversy," and CMS says no minimum is required [3][4].

Before you file: call the provider's billing office

Some denials are billing mistakes. Medicare.gov suggests asking the provider's office whether it submitted the correct information; if not, the office may resubmit [7]. CMS notes that minor errors and omissions aren't fixed through the appeals process [4].

How do I file a redetermination request?

It must be in writing [2][4]. CMS lists two ways [4]:

Form CMS-20027, the Medicare Redetermination Request Form. It asks for the item or service, the date of service, the notice date and why you disagree, and asks you to attach a copy of the notice [5].
A written request that includes your parent's name, Medicare number, the specific service(s) or item(s), the specific date(s) of service, the name of the person filing (or their representative), and why you disagree [4]. Medicare.gov also describes circling the item on a copy of the MSN and explaining in writing why you disagree [6].

Where to send it: the Medicare Administrative Contractor (MAC) that made the decision, at the address on the MSN [2][4][6]. CMS says most MACs also accept appeals through their websites [4].

What to include and keep: any documents that support the appeal, such as a doctor's note [4][6]. The MSN's instructions say to keep copies of everything you send [8]. A delivery method that records the delivery date gives you proof of receipt.

Can I file the appeal for my parent?

Yes, if your parent appoints you. The MSN says a family member or friend can be appointed as a representative in the appeals process [8]. Medicare.gov says to include the "Appointment of Representative" form (CMS-1696) or another written document with the required elements [6]. The form makes the representative the main contact, able to make requests, present evidence and receive communications [9].

What if the 120 days already passed?

If a party shows "good cause," the contractor may extend the deadline. The late request must be in writing and say why it is late [1]. The rule's examples include serious illness; a death or serious illness in the immediate family; records destroyed by fire or another accident; incorrect or incomplete information from the contractor about how to appeal; and never receiving the notice [1]. Form CMS-20027 has a space for the reason [5].

What happens after you file?

The MAC generally decides within 60 days of receiving the request [4][6]. A favorable decision shows on your parent's next MSN; otherwise your parent gets a "Medicare Redetermination Notice." To ask for the next level (a reconsideration), Medicare.gov says you have 180 days after you get that decision [6].

Medicare Advantage or Part D? Different first step, different clock

Coverage	First appeal is called	Deadline in the rule	Send it to
Original Medicare (Part A/B)	Redetermination	120 days from receipt of the notice [1]	The MAC on the MSN [2]
Medicare Advantage	Reconsideration	60 days from receipt of the plan's written notice [10]	The plan [10]
Part D drug plan	Redetermination	60 days from receipt of the plan's written notice [11]	The plan [11]

For both plan types, receipt is presumed 5 calendar days after the notice date, so in practice it is about 65 days from the date printed on the notice; Medicare.gov describes it as 65 days from the date on the plan's denial notice [10][11][12][13]. A plan may extend the time for good cause if the late request is in writing and says why [10][11]. These are standard (non-urgent) appeals; follow the directions in the plan's notice [12][13].

Turning a pile of paperwork into one binder? Our Parent Binder puts visit notes, medication lists, Medicare statements and bills in date order, with every line cited to its page, and drafts letters for you to review and send. See how it works.

Sources

LII / Cornell Law School, "42 CFR § 405.942 - Time frame for filing a request for a redetermination" (as amended Dec. 9, 2009; read October 23, 2026).
LII / Cornell Law School, "42 CFR § 405.944 - Place and method of filing a request for a redetermination" (as amended May 7, 2019; read October 23, 2026).
LII / Cornell Law School, "42 CFR § 405.940 - Right to a redetermination" (read October 23, 2026).
CMS, "First Level of Appeal: Redetermination by a Medicare Contractor" (page last modified March 10, 2026; read October 23, 2026).
CMS, "Medicare Redetermination Request Form - 1st Level of Appeal," Form CMS-20027 (form dated 12/10; read October 23, 2026).
Medicare.gov, "Appeals in Original Medicare" (no date shown; read October 23, 2026).
Medicare.gov, "Medicare Summary Notice (MSN)" (no date shown; read October 23, 2026).
CMS, "Sample Part B Medicare Summary Notice" (illustrative sample; read October 23, 2026).
CMS, "Appointment of Representative," Form CMS-1696 (OMB approval expires 12/31/2028; read October 23, 2026).
LII / Cornell Law School, "42 CFR § 422.582 - Request for a standard reconsideration" (as amended Apr. 23, 2024; read October 23, 2026).
LII / Cornell Law School, "42 CFR § 423.582 - Request for a standard redetermination" (as amended Apr. 23, 2024; read October 23, 2026).
Medicare.gov, "Appeals in Medicare health plans" (no date shown; read October 23, 2026).
Medicare.gov, "Appeals in a Medicare drug plan" (no date shown; read October 23, 2026).

General information to help you organize, not medical, legal or financial advice. Rules change and individual situations differ: check the official source, the notice you received, or a qualified professional. Starry Night is not affiliated with or endorsed by Medicare, CMS, HHS or any health system.