Why Prior Authorizations Get Denied (and How to Prevent It)

Prior authorizations get denied when the request does not give the payer what it needs to approve it: missing or incomplete clinical documentation, a request that does not match the payer's coverage criteria, coding or patient-information errors, or a missed deadline. Many denials are avoidable. A federal review found that 13% of denied Medicare Advantage prior authorization requests met Medicare coverage rules, and 67% of appealed denials in Medicare Advantage were overturned in 2025. Clinics prevent denials by confirming requirements before scheduling, sending complete documentation the first time, following up on a fixed timeline, and appealing denials that should have been approved.

A denied prior auth is expensive in staff time and in patient delay. The American Medical Association's annual survey of 1,000 physicians, reported in July 2024, found that 94% said prior authorization delays patient access to necessary care, and 78% said it often or sometimes leads patients to abandon a recommended treatment. Practices reported completing 43 prior authorizations per physician each week, taking about 12 hours of physician and staff time. This guide covers why denials happen and gives eight fixes, each with a verdict on whether it is worth automating.

Why Prior Authorizations Get Denied

Payers deny a meaningful share of requests. KFF's 2025 analysis found that insurers denied 12% of standard prior authorization requests in Medicare Advantage, 14% in Medicaid managed care, and 18% in ACA Marketplace plans. Denial rates also varied widely by insurer, from 3% to 25% in the ACA Marketplace alone.

Most denials trace back to a short list of causes:

1. Missing or incomplete documentation. The note, lab, imaging report, or signed order the payer needs is not in the packet. In a HHS Office of Inspector General review of 250 Medicare Advantage denials, plans said some requests lacked enough documentation, even though reviewers later found the existing records supported medical necessity.
2. The request does not match the payer's criteria. Each payer has its own policy for each service. The same OIG review found plans denied requests using internal criteria that go beyond Medicare coverage rules, such as requiring an x-ray before approving more advanced imaging. If your documentation does not show that the criteria were met, the request is easy to deny.
3. Coding or patient-information errors. A diagnosis code that does not support the procedure code, a wrong member ID, or a mismatched provider NPI stops a request.
4. Authorization was never obtained, expired, or covers the wrong thing. The visit happens without an approval, the approved dates have passed, or the approval is for a different provider, site, or number of units.
5. Missed deadlines. A payer asks for more information and the request is denied when nobody answers in time.
6. Coverage problems. The patient's plan changed or lapsed between the referral and the visit.

Documentation problems start earlier than most teams realize. Referrals and supporting records often arrive by fax. A 2025 study in JMIR Medical Informatics notes that 88% of Ontario physicians still use fax to share patient information, and the faxed referrals it analyzed averaged 5.6 pages each. A packet that long is hard to check for completeness by eye. Referral gaps also cost visits: Phreesia reports that up to 50% of referrals are not completed, and 13% of patients surveyed said cost was the reason they did not follow through. Authorization delays add one more place for a referred patient to drop off. If your referrals arrive by fax, our post on AI-powered referral intake and scheduling for gastroenterology practices shows how that first step can be automated.

Payers also make mistakes, which is why the last fixes in this guide are about appeals and learning from denials. Many of the fixes below are things your team controls, and a few are not.

8 Ways to Prevent Prior Authorization Denials

1. Confirm the service needs authorization before you schedule

Check authorization requirements before the appointment is booked, and record the answer on the referral. Do not rely on memory or last year's payer list, because requirements change by plan and by code. Use this checklist before you schedule:

• Coverage is active on the date of service
• The plan type is recorded (Medicare Advantage, Medicaid managed care, commercial, ACA)
• You are in network for this plan
• The service or code requires prior authorization (yes, no, or unclear)
• A referral on file is required, and it is on file
• The site of service is the one the payer will approve

Automate? Yes, with staff approval. These checks follow rules and repeat for every referral. Staff should still approve any case marked "unclear."

2. Match the request to the payer's own criteria

Pull the payer's current policy for the specific code and list each criterion it sets, such as symptom duration, conservative treatment tried, or required imaging. Then confirm the chart documents each one. If a criterion is not documented, the clinician decides whether to add the information, change the order, or call the payer before submitting.

Automate? Partly. Finding the policy and comparing it to the chart can be automated. Deciding what is medically necessary cannot, and should stay with the clinician.

3. Run a completeness check before you submit

Most preventable denials come from a packet that was incomplete when it went out. Use the same checklist every time, and do not submit until every line is complete:

• Patient name, date of birth, and member ID match the insurance card
• Ordering provider's name, NPI, phone, and fax
• Procedure code and diagnosis code, with the diagnosis supporting the procedure
• Units or visit count, requested dates, and site of service
• A signed order
• The most recent visit note that describes the problem
• Lab, imaging, and other reports the payer's criteria call for
• Prior treatments tried, with dates and outcomes

If any line is missing, the case gets the status "Missing info" and goes back to whoever can supply it (see fix 6).

Automate? Yes, with staff approval. A checklist is a repeatable comparison, so the same check can run on every case.

4. Set an urgency level and submit on time

Not every request is equally time-sensitive. Agree with your clinicians on three levels, and write down how fast each should be submitted. Payers run on regulated clocks as well. KFF reports that expedited requests must be decided within 72 hours in Medicare Advantage, Medicaid managed care, and ACA Marketplace plans, and that standard requests in Medicare Advantage and Medicaid managed care have a 7-calendar-day deadline starting in 2026 (15 days in the ACA Marketplace). The submit targets below are internal goals, not payer rules, and clinicians set the level.

Automate? Partly. Reading a referral and suggesting a level is a good fit for AI. The final urgency call is clinical, so staff and clinicians confirm.

5. Follow up on a fixed timeline

A submitted request that nobody checks is how information requests turn into denials. Write the follow-up schedule down, and put the next check date on every open case. Adjust the timeline below to each payer's deadline.

Automate? Yes. Checking and logging status is repetitive work. Talking to the payer on an escalation is a person's job.

6. Give every request a fixed status and one owner

Use a short, fixed list of statuses so anyone can see where a case stands. Every open case needs one named owner and one next-action date.

Automate? Partly. Moving a case from one status to the next can be automatic. Deciding who owns an exception is a staffing decision.

7. Answer information requests fast and appeal denials

Reply to payer requests for information the same business day. When a request is denied, read the denial letter for the stated reason and the appeal deadline, then decide whether to appeal, resubmit with better documentation, or change the plan of care. Appeals are worth the effort. KFF found that 67% of appealed Medicare Advantage denials were overturned in 2025, along with 47% in Medicaid managed care and 43% in ACA Marketplace plans, while noting that denials are rarely appealed. The AMA reported a similar pattern: 83.2% of appealed Medicare Advantage requests were overturned in 2022. Ask for a peer-to-peer review when the denial turns on a clinical judgment.

Automate? Partly. Tracking deadlines and assembling the packet can be automated. The clinical argument, and the signature on the appeal, should come from a clinician.

8. Track every denial by reason and fix the pattern

Prevention gets better when you learn from denials instead of only appealing them. Log every denial with the payer, the code, the stated reason, the date, whether it was appealed, and the outcome. Once a month, group the log by payer, by code, and by reason, and look for repeats. A reason that repeats across payers points to your own process, so change the checklist or the documentation template. A reason that repeats at one payer points to that payer's policy, so raise it with your payer contact. This matters because denial rates differ a lot between insurers: KFF found standard-request denial rates ranging from 3% to 25% across ACA Marketplace insurers.

Automate? Yes. Counting and grouping denials is repetitive work that software does well. Staff review the patterns and decide what to change.

A Prior Authorization Workflow That Prevents Denials

Put together, the eight fixes form one workflow. Each step ends with a status, so work never sits without an owner.

Manual vs. Automated Prior Authorization

Automation helps most with repeatable checks, and helps least with clinical judgment. TriFetch's AI employee, Linda, works through the browser the way a staff member does, so it does not need an API integration or an IT project. Staff approve her work before anything is finalized. For a step-by-step walkthrough of what to automate and what to look for in a platform, see our guide to automating prior authorizations.

TriFetch is SOC 2 and HIPAA compliant, signs Business Associate Agreements (BAAs), and offers a 30-day money-back guarantee.

When Automation Is Not the Right Fit

Automation does not solve every denial problem. Be cautious in these cases:

• Low volume. If you submit only a few authorizations a week and your team already runs a checklist and a follow-up schedule, the process fixes in this guide may be all you need.
• Denials that come from clinical judgment. If payers deny because they disagree about medical necessity, the fix is a stronger clinical argument and a peer-to-peer call. Software does not replace that.
• Weak documentation in the chart. Automation can only send what exists. If notes routinely leave out the treatments tried or the findings the criteria call for, fix how the clinic documents first.
• Payers that limit electronic submission. If a payer still requires phone or paper requests, there is less for software to do. Ask any vendor how it handles your top payers by name.
• Denials that are the payer's mistake. If a payer denies requests that meet its own policy, the answer is appeals and escalation to your payer contact.

If you are unsure, start with the free fixes and track your denial rate for a month. The numbers will show whether the problem is your process or the payer.

How to Get Started

1. Measure your baseline. Count requests submitted, denials, denials by reason, and how many were appealed.
2. Make the free fixes first. Adopt the pre-scheduling checklist, the completeness check, the urgency levels, and the follow-up timeline.
3. Pick your top payers and codes. A handful of payer and code pairs usually account for most of your volume. Start there.
4. If you automate, keep approval on. Review the automated work for the first few weeks before loosening anything.
5. Compare against your baseline. After 30 days, check denial rate, time to submission, and hours of staff time on follow-up.

Frequently Asked Questions

Why do prior authorizations get denied?

Prior authorizations get denied when the request does not give the payer what it needs to approve it. The most common causes are missing or incomplete clinical documentation, a request that does not match the payer's coverage criteria, coding or patient-information errors, authorization that was not obtained or has expired, and missed deadlines for information requests. Some denials are also payer errors: a federal review found that 13% of denied Medicare Advantage prior authorization requests met Medicare coverage rules.

How can clinics prevent prior authorization denials?

Clinics prevent denials by confirming whether a service needs authorization before scheduling, matching the request to the payer's criteria, running a completeness check before submitting, submitting by urgency level, following up on a fixed timeline, and answering payer information requests the same business day. A fixed status list with one owner per case keeps requests from stalling.

How long does a prior authorization take?

Insurers' median response time for standard requests was about 1 day in 2025, according to KFF, but the regulated deadlines are longer. Expedited requests must be decided within 72 hours. Standard requests in Medicare Advantage and Medicaid managed care have a 7-calendar-day deadline starting in 2026, and 15 days in the ACA Marketplace. Commercial plan deadlines vary, so check each payer's contract and state rules.

Should we appeal a denied prior authorization?

Usually yes, if the request met the payer's criteria or the denial reason can be fixed with more documentation. KFF found that 67% of appealed Medicare Advantage denials, 47% of Medicaid managed care denials, and 43% of ACA Marketplace denials were overturned in 2025, and that denials are rarely appealed. Read the denial letter for the reason and the appeal deadline, and ask for a peer-to-peer review when the denial turns on clinical judgment.

Can AI automate prior authorizations?

Partly. AI works well on repeatable steps: checking coverage and authorization requirements, running a completeness check, preparing submissions, scheduling follow-ups, and tracking status. Clinicians should still confirm medical necessity and write appeals, and staff should approve automated work before it is sent. Each fix in this guide carries a yes, no, or partly verdict.

When is prior authorization automation not worth it?

Automation is a weaker fit when volume is low and a checklist already works, when denials come from disagreements about medical necessity, when chart documentation is routinely incomplete, or when payers limit electronic submission. Fix the process first, then measure whether the remaining work is repetitive enough to automate.

The Bottom Line

Most prior authorization denials come from a few causes your team can control: missing documentation, requests that do not match payer criteria, errors, and missed follow-up. Start with the checklists and timelines, which cost nothing. Then automate the repeatable checks and keep clinicians on the judgment calls and the appeals.

Sources

• KFF, Prior Authorization Metrics Provide New Insights into Insurer Practices, but Gaps Remain (2025 denial, overturn, and timeframe data)
• HHS Office of Inspector General, Some Medicare Advantage Organization Denials of Prior Authorization Requests Raise Concerns About Beneficiary Access to Medically Necessary Care (2022)
• American Medical Association, Exhausted by prior auth, many patients abandon care: AMA survey (2024)
• American Medical Association, Prior authorization denials up big in Medicare Advantage
• JMIR Medical Informatics, A Unique Way to Axe the Fax Through Using Business Automation Workflow to Expedite eReferral Adoption (2025)
• Phreesia, patient referral habits (referral completion and follow-through survey)