Medicare Redetermination Form
A redetermination is the first level of appeal for an Original Medicare Part A or Part B claim. You send it to the Medicare Administrative Contractor (MAC) that processed the claim, on form CMS-20027 or in any written request that carries the same information.
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The Facts in One Place
This covers Original Medicare. A Medicare Advantage plan runs its own first level of appeal, and the plan's notice says how.
| Level | 1 of 5 in the Original Medicare appeal process. |
| Who decides | MAC staff who were not involved in the initial claim determination. |
| Deadline | 120 days from the date you receive the initial determination. CMS presumes receipt 5 days after the date on the notice, unless there is evidence you got it later. |
| Form | CMS-20027, or any written request with the required information. |
| Minimum amount | None. |
| Decision | Generally within 60 days of the MAC receiving the request. |
| If you lose | Level 2: reconsideration by a Qualified Independent Contractor (QIC). File within 180 days of receiving the redetermination notice, on form CMS-20033. |
What the Request Has to Contain
If you do not use the form, CMS accepts a written request that includes all of these:
- 1The beneficiary's name.
- 2The Medicare number.
- 3The specific services or itemsyou want redetermined.
- 4The specific dates of service.
- 5The name of the partyor of the party's representative.
- 6An explanation of why you disagreewith the decision.
The form asks for the same things, so it is the easy way to not miss one. Send the request to the address on the remittance advice, or use your MAC's website if it takes requests electronically. CMS counts the request as filed on the date the MAC receives it, so keep proof of delivery and a copy of everything you send.
Check That There Is a Decision to Appeal
A claim returned as unprocessable, usually with remark code MA130, was never adjudicated. The fix is a new, corrected claim. A MAC can dismiss a redetermination request when there is no initial determination, and the filing clock on the service keeps running while you wait. A claim denied because it was filed late is not an initial determination either: see the Medicare timely filing limit.
What to Attach
Attach every document that supports your case now. The reconsideration at level 2 is the last point where you can add evidence freely: after it, the later levels consider new evidence only if you show good cause for the delay.
- A copy of the remittance advice that shows the denial and its codes.
- The records that answer the specific reason code, not the whole chart. The denial code page for your code lists what that is.
- Where the denial is about coverage, the policy it applied, for example the LCD named by remark code N115, and the lines in the record that meet it.
- If you are late, a written reason for the late filing.
Codes That Often End in a Redetermination
Our reading, not a CMS list. These are the Medicare denials where the answer is usually in the record, so a level 1 appeal with the right documents is the normal next step.
CO 50
The payer decided the service was not medically necessary.
Read the CO 50 pageCO 151
The payer says the records do not support this many units or visits.
Read the CO 151 pageCO 97
The payer says this is already paid inside another service.
Read the CO 97 pageCO 167
The diagnosis billed is not covered for this service.
Read the CO 167 page
For commercial payers the deadline comes from your contract, not from CMS. See what an appeal letter has to contain for how to find it.
Sources
Deadlines and requirements on this page are from CMS, linked here. The code classifications are our own reading.
- First Level of Appeal: Redetermination by a Medicare Contractor, CMS.gov
- Medicare Redetermination Request Form (CMS-20027), CMS.gov
- Medicare Parts A & B Appeals Process (MLN006562), CMS, September 2025
Your Questions Answered
What is a Medicare redetermination?
The first level of appeal for an Original Medicare Part A or Part B claim. Staff at the Medicare Administrative Contractor (MAC) who were not involved in the original decision review the claim again.
Which form do I use to request a redetermination?
Form CMS-20027, the Medicare Redetermination Request Form. CMS also accepts any written request that contains the same required information.
How long do I have to file a redetermination?
120 days from the date you receive the initial determination. CMS presumes you received it 5 days after the date on the notice, unless there is evidence you did not. A late request must give a reason, and the MAC decides whether there was good cause.
How long does a redetermination take?
The MAC generally sends its decision within 60 days of receiving the request.
Is there a minimum dollar amount to request a redetermination?
No. There is no minimum amount in controversy at this level.
What happens if the redetermination is unfavorable?
The next level is a reconsideration by a Qualified Independent Contractor (QIC). File it within 180 days of receiving the redetermination notice, on form CMS-20033 or in a written request.
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