A denial code names the problem. It does not name the fix. The same code on a remit means one thing at a commercial plan and another at a Medicaid managed care plan, and each payer wants its own paperwork, its own address, its own evidence and its own filing window. A payer-specific playbook turns that difference into a page your team can work from.
What this covers
- The group code before the reason number decides who pays. CO means the practice absorbs the adjustment; PR means the patient can be billed.
- Filing windows come from the plan type. Medicare fee-for-service runs on 120 days, ERISA group plans on a 180-day floor, and Medicaid managed care on 60 days before a state fair hearing opens.
- Every payer page needs seven fields: plan family, top denial reasons, appeal address and portal, filing window with the clock start, documentation quirks, the appeal ladder, and a named owner.
- Behavioral health claims add prior authorization terms. ABA denials often turn on an expired authorization, exhausted units, or a mismatch in code, provider or place of service.
- All ABA CPT codes carry a Medically Unlikely Edit adjudication indicator of 3, so a preauthorized, correctly coded, medically necessary claim is payable above the edit.
The code tells you what the payer decided. The payer tells you what it takes to change that decision.Build the page around the payer, not the code.
One page per payer, one owner per page. That is the whole method. This article covers how to read a denial by group code, the seven fields a payer page carries, where each filing window comes from, what behavioral health claims add, and how to build and keep the set current. It uses denial management as the frame because a playbook only pays off when it feeds the work queue.
Read the group code before the reason code
A Claim Adjustment Reason Code is half a message. The X12 standard pairs each reason code with a group code, and the group code assigns financial responsibility. CO is a contractual obligation, so the practice absorbs the adjustment. PR is patient responsibility, so the patient can be billed. The same reason number under each prefix leads to opposite decisions, so read the prefix first.
| Code | What it means | What the fix usually is |
|---|---|---|
| CO-197 | Prior authorization absent or not matched | Check the payer authorization matrix. Resubmit with the authorization number if it exists, or appeal with the approval letter. |
| CO-50 | Not medically necessary | Pull the payer medical policy, then appeal with the criteria cited in the denial and the notes that meet it. |
| CO-16 | Missing claim information | Read the RARC for the missing element, correct the claim and resubmit. |
| CO-45 | Charge exceeds the allowed amount | Usually a contractual write-off. An appeal rarely changes it. |
| PR-96 | Non-covered charge, patient responsibility | Verify the benefit. Bill the patient only when the group code is PR. |
The code narrows the problem. The payer sets everything else: the form, the portal, the evidence it will read, and the date the request has to arrive. That is the reason one page per payer beats one page per code.
A denial that starts with CO cannot be billed to the patient under most contracts. A denial that starts with PR can. The reason number does not change that. The prefix does.
The seven fields on every payer page
A payer page is short by design. If it does not fit on one screen, the team will not read it under a deadline. These seven fields cover what a biller needs at the moment a denial lands.
Name the exact plan: Medicare Advantage, commercial fully insured, self-funded ERISA, or Medicaid managed care. The plan family sets the appeal rules.
List the codes that drive the most dollars, with the count from your own remits. Rank by money rather than by frequency.
Record the mailing address, the portal path, and any rule that requires electronic submission.
State the number of days and the event the clock runs from: the notice date, the receipt date, or the date of service.
Note what this payer reads: a signed order, the progress note, the authorization letter, the medical policy page.
Lay out each level in order, with its own deadline and its own decision maker.
Name one person and a date to revisit the page. A page without an owner goes stale in a quarter.
A payer that requires electronic reconsideration before it will accept an appeal changes the first step. UnitedHealthcare runs a two-step process for most network providers: file a claim reconsideration, then file an appeal only if the reconsideration holds. The two steps share a single 12-month window.
Where each filing window comes from
The deadline is not a payer preference. It comes from the plan type. Medicare fee-for-service, ERISA group health plans, and Medicaid managed care each set their own clock, and a commercial contract can shorten the one it uses.
| Plan type | First-level window | Clock starts | Who decides |
|---|---|---|---|
| Medicare fee-for-service | 120 days | Receipt of the initial determination, presumed 5 days after the notice date | The MAC |
| Medicare reconsideration, level 2 | 180 days | Receipt of the redetermination | The QIC |
| ERISA group health | 180 days | Receipt of the adverse benefit determination | The plan |
| Medicaid managed care | 60 days | The date on the plan notice | The MCO |
| Medicaid state fair hearing | 90 to 120 days | The MCO notice of resolution | The state agency |
| Commercial contract | Varies | Usually the denial or remit date | The payer |
The numbers come from the rules rather than from a payer handbook. A Medicare redetermination runs 120 days from receipt of the initial determination, and the notice is presumed received five calendar days after the date on it. A group health plan governed by ERISA must give at least 180 days to file an internal appeal. Medicaid managed care gives 60 days to appeal to the plan, then no less than 90 and no more than 120 days to request a state fair hearing, which the state must decide within 90 days.
Commercial plans sit on the contract. Aetna standard is 180 days to file an initial claim-payment dispute, with state exceptions that run longer, such as one year in Arizona and 365 days in Maryland. Cigna asks for the appeal within 180 days and allows 60 days to process it, unless the provider agreement or state law says otherwise. Both defer to the contract, so the contract is the source to read.
For a non-grandfathered group or individual plan, external review is a separate deadline: at least four months from the final internal adverse benefit determination. An independent review organization decides in 45 days, or 72 hours if the case is expedited, and the decision binds the plan.
Every number here is a rule or a floor. The deadline printed on the denial notice controls, and a payer contract can set a shorter one. Calendar the date on the letter the day it arrives.
What behavioral health claims add
Behavioral health claims carry an extra layer: the prior authorization. For ABA and similar services, the authorization names the codes, the units, the dates, the rendering provider and the place of service. A claim that falls outside any of those terms can be denied even when the therapy was appropriate. Practices that bill ABA should read specialties alongside this playbook, because the denial mix differs by service line.
- Expired authorization: sessions continued past the end date.
- Exhausted units: care delivered after the approved units were used.
- Code mismatch: the claim uses a different CPT code than the authorization.
- Provider mismatch: the rendering or supervising provider is not on the authorization.
- Place-of-service mismatch: the authorization is clinic-only but the session was in the home.
Some of these denials are edits, not coverage decisions. All ABA CPT codes carry a Medically Unlikely Edit adjudication indicator of 3. Under the CMS edit guidance, an indicator 3 code is payable above the edit when the service was actually provided, correctly coded and medically necessary. A prior authorization already settles medical necessity, so it should not be reopened at claims processing.
The unit math matters. Timed ABA codes bill in 15-minute units, so a 60-minute session of 97153 is four units. The Medicare edit for 97151, the behavior identification assessment, is eight units, or two hours, per day. Medicaid lists a larger figure, 32 units or eight hours per day, and the ABA Coding Coalition has argued that the Medicaid number reflects how assessment is actually delivered.
The Mental Health Parity and Addiction Equity Act bars a quantitative treatment limit on a mental health benefit unless the same limit applies to substantially all medical and surgical benefits in the same classification. A visit cap or a units cap applied only to ABA is a parity question as much as a billing one.
A Medically Unlikely Edit denial that starts with CO is the practice contractual adjustment, not patient responsibility. Billing the family for it invites a complaint and, under parity rules, a regulator attention.
Build the playbook in one pass
Start with data you already have. A year of remits will rank the payers and the reasons faster than any template.
Group every denied or zero-paid line by payer and by CARC and RARC pair. Total the dollars in each group.
Open a page for each payer that holds the top 80 percent of denied dollars. Ignore the long tail until the core pages are done.
For each top reason on that payer, write the exact steps, the evidence, the address and the deadline. One reason, one recipe.
Enter each filing window as a task template in the work queue, timed to the clock start on the page.
Assign one person per payer. That person owns the page, the queue and the payer relationship.
Run a real denial through the page end to end. Fix whatever the page left out before you trust it.
- Plan family and product named exactly.
- Top denial reasons ranked by denied dollars, with counts.
- Appeal address, portal path and any electronic-submission rule.
- Filing window with the clock start spelled out.
- The documentation this payer actually reads.
- Each appeal level, in order, with its own deadline.
- One owner and a review date.
The work queue is where the playbook earns its keep. A denial should not sit because no one knew the window. Tie each open denial to its payer page so the deadline and the evidence travel with the claim.
Keep the pages current and give each one an owner
Payer policy moves. A coverage policy is revised, a portal replaces a fax number, a contract renews with a shorter window. A playbook that is right in January can be wrong by summer. Build a review rhythm and a place to record what changed.
The credentialing calendar is a natural trigger. Enrollment, network status and revalidation changes often change the address, the portal and the appeal path on the page. When a provider is added to a payer or moves plans, update the page the same week.
Open every page once a quarter. Check the address, the portal and the top denial reasons against the last 90 days of remits.
Date every edit and note what changed and why. A page with a history is easier to trust.
When a payer posts a new medical policy or a federal rule takes effect, update the affected pages.
Send recurring denial reasons back to coding and intake so the fix moves upstream.
One federal change is worth a line on every payer page this year. Under CMS-0057-F, Medicare Advantage, Medicaid, CHIP and marketplace plans had to begin giving a specific reason for each prior authorization denial in 2026, whatever channel the request arrived through. A specific reason is easier to appeal than boilerplate. The payer pages should capture that reason in the queue so the appeal writes itself.
Payer denial playbook questions
It is one page per payer that lists that payer top denial reasons, appeal address and portal, filing window and clock start, documentation quirks, appeal ladder, and the person who owns it. The point is to remove guesswork at the moment a denial lands. A biller opens the page, follows the recipe for that reason, and files before the window closes.
A code narrows the problem but does not name the fix. CO-197 means a prior authorization is missing, yet one payer accepts a resubmission with the authorization number while another requires a formal appeal. The paperwork, the address, the evidence and the deadline all change with the payer. One page per payer keeps those differences in front of the biller.
A redetermination, the first level, must be filed within 120 days of receipt of the initial determination. The notice is presumed received five calendar days after its date. If the MAC upholds the denial, a reconsideration by a qualified independent contractor is next, within 180 days of receipt of the redetermination. Later levels run on 60-day windows.
It depends on the contract and the plan type. ERISA group health plans must allow at least 180 days to file an internal appeal. Aetna standard dispute window is 180 days, with longer state exceptions. Cigna asks for 180 days. UnitedHealthcare runs a reconsideration then an appeal inside a combined 12-month window. Always use the date printed on the denial notice.
Medicaid runs on two tracks. A managed care denial is appealed to the plan first, within 60 days of the notice, and the plan decides in 30 days. If the plan upholds it, the state fair hearing opens, with no less than 90 and no more than 120 days to request it. A fee-for-service denial goes to the state hearing directly.
All ABA CPT codes carry a Medically Unlikely Edit adjudication indicator of 3. Under CMS guidance, an indicator 3 code is payable above the edit when the service was provided, correctly coded and medically necessary. Prior authorization already establishes medical necessity, so an edit that ignores the authorization is a coding or parity issue to appeal.
One named person per payer. That person keeps the page current, watches the work queue for that payer, and holds the relationship with the payer provider services team. Shared ownership fails because no one checks the address, the portal or the window until a deadline is already lost. Pair the page with a quarterly review date.
The bottom line
The code names the problem, but the payer sets the fix. Build one page per payer, put the window and the evidence on it, and name the person who owns it. A playbook that lives in the work queue keeps denials moving instead of aging.
How many of your denials are past their filing window right now?
The MedFactor team builds payer-specific denial pages, wires the filing windows into the work queue, and works the appeals. Send us a month of remits and we will show you which payers cost you the most and where the deadlines are being missed.
Request a free denial auditThis article is general information about payer appeal rules and denial workflows, not legal advice, and the deadline on your own denial notice or provider contract controls.
