This resource gives the denial appeal letter that fits each denial family, from medical necessity to coordination of benefits, with the evidence to attach, the appeal level the request belongs to, and the line that most often sinks the letter. The mechanics that apply to every appeal follow: corrected claim or appeal, the deadline, the signature and the criterion.
How to use these denial appeal letter templates
A denial appeal letter is a written challenge to a payer decision, not a second copy of the claim. Which template you need is set by the CARC the remittance carried, because each family asks a different question and a different reviewer answers it. This resource groups the letters by family, names the evidence each one has to attach, and states the level the request belongs to.
Two checks come before you open any template. Read the code on the 835 and the remark code beside it, since the X12 code lists define the reason and the payer’s group code prefix decides who absorbs the amount. Then decide whether the error was yours or the payer’s: a claim you got wrong gets corrected, and only a wrong decision gets appealed.
Every appeal becomes part of the administrative record, and at later Medicare levels only evidence filed with the first request or with good cause is considered. Write for the reviewer who has to find the criterion, not for the person who reads it first.
| Action | What it is | When it applies |
|---|---|---|
| Corrected claim | A replacement claim submitted with the right data on the form. | The error is yours: a wrong modifier, a missing drug code, a wrong date of service. |
| Appeal | A written challenge to the payer’s decision, filed at the level the notice names. | The decision is wrong: CARC 50 on medical necessity, CARC 197 on authorization, CARC 29 on filing time. |
| Reopening | The payer’s own review of a processed claim, requested with no appeal right attached. | A clerical error, or a late-filing exception the contractor can apply on its own motion. |
| Redetermination | The first level of a Medicare appeal, decided by the MAC that processed the claim. | Original Medicare Parts A and B claims, within 120 days of the initial determination. |
The denial families, and the code each one arrives as
Seven families cover most of the denials a practice appeals, and the X12 wording tells you which family you are in before you read a single note. Check the live list rather than a saved screenshot, because codes get retired: CARC 15, which vendor pages still cite for a missing authorization number, carries a stop date of 1 May 2018 on the X12 list.
| Denial family | CARC | Reading on the current X12 list |
|---|---|---|
| Medical necessity | 50 | Non-covered because the payer does not deem the service medically necessary. |
| Authorization absent | 197 | Precertification, authorization, notification or pretreatment absent. |
| Authorization does not apply | 284 | The authorization may be valid but does not apply to the billed services. |
| Filing time expired | 29 | The time limit for filing has expired. |
| Bundling and coding | 234 | This procedure is not paid separately. |
| Duplicate | 18 | Exact duplicate claim or service. |
| Coordination of benefits | 22 | The care may be covered by another payer under coordination of benefits. |
| Non-covered benefit | 204 | The service, equipment or drug is not covered under the patient’s current benefit plan. |
| Sent to the wrong payer | 109 | Not covered by this payer or contractor; send the claim to the correct payer. |
Two of these are routinely misread. CARC 29 for expired filing time is not an appealable initial determination on a Medicare claim, so the practical route is a reopening request or a documented good-cause statement. CARC 22 is usually a routing problem: the answer is to send the claim to the payer named first in the coordination of benefits order, and to appeal only if that payer denies it. The claim denial codes reference lists the rest of the current set.
What the letter has to do, family by family
The job of the letter is to answer the criterion the payer applied. State the code and the line, restate the criterion in the payer’s own words, then point to the facts and the chart page that meet it. A biller who writes to the criterion gets a different result than one who writes about the patient’s need for care.
| Family | The letter’s job | Evidence to attach | Level it belongs to |
|---|---|---|---|
| Medical necessity | Tie every denied line to the coverage criterion the payer applied. | The policy or local coverage determination the denial names, chart notes, test results, failed conservative care dates, a letter of medical necessity. | First level; some commercial plans take a peer-to-peer review first. |
| Authorization absent | Show the authorization exists, or that the service was urgent and none could be obtained. | The authorization number and date, the portal or fax confirmation, notes showing urgency, the payer’s retro-authorization policy. | First level; some plans run an authorization reconsideration before the claim appeal. |
| Retroactive authorization | Show the service meets the payer’s own criteria for authorization after the fact. | The retro-authorization request and answer, the clinical reason treatment started before approval, the effective dates claimed. | First level. |
| Timely filing | Prove the claim reached the payer inside the window. | Clearinghouse acceptance report, the 277CA, the payer’s own receipt date, the original claim, a good-cause statement. | First level when an initial determination exists; a reopening when it does not. |
| Coding and bundling | Show the pair is payable together with the modifier and the documentation of a distinct service. | Operative note, separate site or time documentation, the edit and its modifier indicator, the coding rationale. | First level; a corrected claim when the code itself was wrong. |
| Duplicate | Show the two claims are different services, or withdraw the second one. | Both claim numbers, the dates of service, provider and payer identifiers side by side. | First level; withdraw the claim when it is a true duplicate. |
| Non-covered service | Show the service is a covered benefit, or that a valid notice shifted it to the patient. | The plan benefit document, the policy the payer cites, the signed advance beneficiary notice if one applies. | Plan appeal; a Medicare redetermination is the first level. |
| Coordination of benefits | Establish the order of benefits and attach the other payer’s action. | The other payer’s explanation of benefits or 835, the MSP questionnaire, the primary payer’s denial, the corrected secondary claim. | Not an appeal at first: correct and route the claim, then appeal if the right payer denies. |
A template should ask for a specific remedy, and it should name it. It cannot state that the appeal will be paid, and it should not. Ask for the denial to be reversed and the claim reprocessed, then leave the decision with the reviewer.
Medical necessity is the family where the letter carries the most weight, and the one where the payer publishes the standard it used. The medical necessity denial appeals guide walks through reading the criterion against the chart, which is the same motion every other family needs.
The sentence that most often sinks a letter
Each family has one line that sounds like an argument and proves nothing. The pattern is the same in all of them: the line restates the conclusion the payer already rejected. Delete it and put the record fact or the policy sentence that answers the criterion in its place.
| Family | The line that sinks it | What to write instead |
|---|---|---|
| Medical necessity | The service was medically necessary. | The criterion, then the note date and the finding that meets it. |
| Authorization absent | Authorization was obtained. | The authorization number, its date, and the portal reference that confirms it. |
| Timely filing | The claim was filed timely. | The clearinghouse acceptance date and the payer’s own receipt date. |
| Coding and bundling | The codes were correct. | The separate service documented, and the modifier indicator that permits it. |
| Duplicate | This is not a duplicate. | Both claim numbers and the differing dates of service. |
| Non-covered service | The patient needs this service. | The benefit language that covers it, or the signed notice that shifts it. |
| Coordination of benefits | The other payer denied it. | The other payer’s explanation of benefits and the reason it gave. |
Deadlines that decide the level, and the clock at each one
The deadline decides the level, and the level decides who answers. For Original Medicare, 42 CFR 405.942 sets 120 calendar days from the initial determination to request a redetermination, the first level, and the contractor can extend it when good cause is shown. The window runs from when the practice got the notice.
The second level runs from the redetermination notice: 180 days for a reconsideration, or 60 days when the MAC dismissed the request. Levels three, four and judicial review each allow 60 days, and a minimum amount in controversy applies at levels three and five. A dismissal is itself a decision that can be disputed.
| Level | Who decides | Days to file | Form the notice names |
|---|---|---|---|
| First, redetermination | MAC staff who were not involved in the original claim determination | 120 from the initial determination | CMS-20027, or a written request with the required elements |
| Second, reconsideration | Qualified Independent Contractor | 180 from the redetermination notice; 60 after a dismissal | CMS-20033 |
| Third, OMHA hearing | Administrative law judge or an attorney adjudicator | 60 from the QIC notice | OMHA-100, OMHA-100A or OMHA-104 |
| Fourth, Council review | Medicare Appeals Council | 60 from the OMHA notice | DAB-101 |
| Fifth, judicial review | U.S. district court | 60 from the Council notice | No HHS form is available |
Days to file a Medicare appeal, by level
Source: CMS MLN006562, Medicare Parts A and B Appeals Process, September 2025. Receipt is presumed 5 days after the notice date unless the record shows otherwise.
A commercial plan sets its own clock, and that clock is not the Medicare clock. Read the appeal rights paragraph on the denial notice for that payer, then check its provider manual, the way a biller checks timely filing limits by payer instead of applying one rule everywhere. Filing at the wrong level produces a dismissal, not a review.
How long the reviewer has to decide, at each level
Source: CMS MLN006562, Medicare Parts A and B Appeals Process, September 2025.
Who signs it, and how to help the reviewer find the criterion
The signature turns on who holds the appeal right. A participating provider appeals its own claim and signs the request. When the practice appeals on the patient’s behalf, the appointment of representative is what lets the adjudicator release records and decide, and it has to be filed with the request rather than after it.
- Match the signature to the party that holds the appeal right, not to whoever has time that week.
- File the appointment of representative with the request when the patient owns the right.
- Name the criterion the payer applied, with its policy number and the version date.
- Point to the chart page and the finding, so the reviewer does not have to hunt for either.
- State the remedy as reversal of the denial and reprocessing of the claim.
- List the attachments on the letter, in the order they are clipped.
The reviewer is looking for two things: the criterion being answered, and the evidence that answers it. A letter that makes either one hard to find gets denied on the record as written, which is the most avoidable denial in the file. The denial management workflow treats the letter as one step with a deadline attached, not a document to write from scratch.
Where to send it, and why the payer owns its own process
A payer owns its own appeal process, so the address, the portal and the fax number come from that payer’s provider manual rather than from a template. Noridian, a Part B Medicare Administrative Contractor, asks providers to file redeterminations through its portal and publishes separate destinations for each level, with the second level going to the QIC rather than back to the MAC.
- 01
Read the instruction on the notice
The denial letter and the remittance name the entity and the address for the next level. Start there, not with a template saved from another payer’s appeal.
- 02
Confirm the entity for the level
A reconsideration goes to the Qualified Independent Contractor, not back to the MAC. Sending a level two request to a level one address is a dismissal waiting to happen.
- 03
Log the receipt date
The clock runs from receipt. Save the portal confirmation, the fax report or the certified mail receipt with the appeal file, because that date is the one that gets argued later.
For Medicare claims, the Medicare Claims Processing Manual chapter 29 holds the contractor instructions, and the appeals process booklet carries the five levels, the forms and the clocks in one summary table. Neither replaces the payer’s own notice, which is the document that governs where a specific appeal goes.
A last read before the denial appeal letter goes out
Read the letter once as the reviewer would. If the answer to any line below is no, it is not ready to send, and a late filing costs more than a day’s delay spent fixing the evidence.
- The CARC and RARC from the remittance are quoted correctly, checked against the live X12 list.
- The criterion the payer applied is named, with the policy and the version date.
- Every fact in the letter has a chart page, a claim line or an attachment behind it.
- The attachments listed are attached, and the file copy matches what was sent.
- The level matches the deadline, and the entity receiving it decides that level.
- The remedy asks for reversal and reprocessing, with no promise of payment.
A request filed at the wrong level, or after the window, usually ends in a dismissal. A dismissal is a decision, so it has to be appealed too, which adds a level of work to a claim that already had a deadline slip.
Questions practices ask us about this
What is the difference between a denial appeal letter and a corrected claim?
A corrected claim replaces a claim that was wrong on the form, such as a wrong modifier, a missing drug code or a wrong date of service, and it is submitted as a new claim with the payer’s correction indicator. An appeal challenges the payer’s decision rather than your data, and it is filed with the entity and inside the window the denial notice names. If the record shows the payer chose wrongly, you appeal. If the record shows you billed wrongly, you correct and resubmit.
How long does a practice have to file a Medicare redetermination?
120 calendar days from receipt of the initial determination, under 42 CFR 405.942. The contractor presumes receipt five days after the notice date unless the evidence shows otherwise, and it can extend the window when good cause is shown, such as a serious illness, destroyed records or misleading information from the contractor. A request that misses the window without good cause gets dismissed, and a dismissal then has to be appealed on its own.
Which denial codes mean medical necessity and which mean authorization?
CARC 50 is the medical necessity code on the current X12 list: the payer does not deem the service medically necessary. Authorization denials arrive mainly as CARC 197 for a missing authorization, and CARC 284 when the authorization is valid but does not apply to the billed services. CARC 15, which vendor pages still cite for a missing authorization number, carries a stop date of 1 May 2018 and is no longer valid.
Does a CARC 29 denial mean the claim should be appealed?
Usually not. CARC 29 means the time limit for filing has expired, which is not an initial determination on a Medicare claim, so there is no appeal right to exercise. The practical routes are a reopening request, where a clerical error or a listed exception lets the contractor review the claim, or a documented good-cause statement if the notice itself was never received. Check the payer’s provider manual for which of those it accepts.
Who should sign a denial appeal letter?
The party that holds the appeal right signs it. A participating provider has appeal rights on its own claims and signs the request. When the practice appeals on the patient’s behalf, the patient holds the right, and an appointment of representative has to be completed and filed with the request so the adjudicator can release records and decide the case. Keep a signed copy in the appeal file.
Can an appeal letter promise that the claim will be paid?
No, and a template that does is a liability. State the specific remedy you are asking for, which is reversal of the denial and reprocessing of the claim, and set out the criterion and the evidence that support it. The reviewer makes the payment decision. Promising an outcome in the letter does not influence that decision, and it can create a patient or client expectation the practice then has to manage.
Where do I find the right address or portal for an appeal?
On the denial notice and the remittance, which name the entity that decides the next level, and in that payer’s provider manual, which carries the current address, portal and fax number. Medicare addresses differ by level, and a reconsideration goes to the Qualified Independent Contractor rather than back to the MAC. Confirm the entity and the destination each time, because a request filed with the wrong one is dismissed.
Want this fixed in your practice?
We run full-cycle billing, coding, credentialing and denial work for practices across the country. Send us a few months of claims and we will show you where the money is going.
Book a free billing review- CMS, MLN006562, Medicare Parts A and B Appeals Process (September 2025). cms.gov/files/document/mln006562-medicare-parts-b-appeals-process.pdf
- eCFR, 42 CFR 405.942, Time frame for filing a request for a redetermination. ecfr.gov/current/title-42/chapter-IV/subchapter-B/part-405/subpart-I/section-405.942
- CMS, Medicare Claims Processing Manual, Chapter 29, Appeals of Claims Decisions. cms.gov/regulations-and-guidance/guidance/manuals/downloads/clm104c29.pdf
- X12, Claim Adjustment Reason Codes (current list). x12.org/codes/claim-adjustment-reason-codes
- Noridian Healthcare Solutions, JF Part B, redetermination versus reconsideration forms and filing addresses. med.noridianmedicare.com/web/jfb/article-detail/-/view/10534/redetermination-versus-reconsideration-forms-appeals-newsletter-part-18-1
- CMS, Original Medicare (fee-for-service) appeals. cms.gov/medicare/appeals-grievances/fee-for-service
