Why are my insurance claims getting denied? 9 common reasons and how to fix them
The short answer
Most insurance claim denials come from a handful of fixable problems: coverage not verified, missing prior authorization, registration errors, coding mismatches, missing documentation and late filing. Checking eligibility before every visit and scrubbing claims before they go out prevents most of them.
The 9 most common reasons claims get denied
01Coverage wasn't verified
The patient's plan changed, ended, or doesn't cover the service. This is one of the most common and most preventable denials.
Fix: Run an eligibility check before every visit, not just the first one, and re-scan insurance cards at every check-in.
02Missing prior authorization
Many imaging studies, procedures and specialty drugs need approval from the insurer before the service. Without it, the claim is denied even if the care was medically necessary.
Fix: Keep an up-to-date list of which payers require authorization for your most common services, and check it when the order is placed.
03Registration and demographic errors
A misspelled name, wrong date of birth or incorrect member ID is enough to stop a claim.
Fix: Match registration exactly to the insurance card, and have a second person spot-check new patient entries.
04Coding errors and mismatches
The diagnosis code doesn't support the procedure, a modifier is missing or wrong, or a code is outdated after the yearly code update.
Fix: Use claim scrubbing software, update your code lists every year, and run a periodic coding audit.
05Missing or weak documentation
The note doesn't clearly support medical necessity or the level of service billed, so the payer refuses or asks for records.
Fix: Build EMR templates that prompt for the details payers look for, and give providers feedback from coding audits.
06Duplicate claims
Resubmitting a claim that is still being processed, instead of checking its status, gets it denied as a duplicate and slows payment further.
Fix: Check claim status in the payer portal first, and send corrected claims with the right resubmission code.
07Missed timely filing limits
Every payer sets a deadline for submitting claims. Medicare's is generally 12 months from the date of service, and many commercial plans allow far less.
Fix: Keep a filing-limit chart for every payer you bill, and submit claims within days of the visit, not weeks.
08The provider isn't credentialed with that payer
If a provider is new, recently moved, or let a re-credentialing date lapse, the insurer may deny every claim under their name.
Fix: Track effective dates and expirations for every provider and payer in one place. See our credentialing answers.
09Coordination of benefits problems
When a patient has more than one insurance plan, billing the wrong one first, or not having the other insurer's information, leads to denials.
Fix: Ask about other coverage at every check-in and confirm which plan is primary before billing.
What to do when a claim is denied
- Read the reason code. The remittance shows a denial code (CARC) and often a remark code (RARC) that explain exactly why.
- Decide: correct or appeal. Simple errors, like a typo or a missing modifier, are fixed and resubmitted. Disagreements about coverage or medical necessity are appealed.
- Act before the deadline. Appeal windows vary by payer. Note the deadline the day the denial arrives.
- Track the pattern. Log every denial by reason and payer. The same few reasons usually repeat, and fixing them upstream is worth more than winning appeals.
How to prevent denials before they happen
When to get help
If denials are rising, A/R over 90 days keeps growing, or nobody has time to work appeals, it's time for a second set of eyes. We'll review your denials and show you where they start, free.
Frequently asked questions
What's the difference between a rejected claim and a denied claim?
A rejected claim never made it into processing because of an error, like a bad member ID, so you fix it and send it again. A denied claim was processed and the payer refused to pay, so you correct it or file an appeal.
How long do I have to appeal a denied claim?
It depends on the payer. For Medicare, a first-level appeal (redetermination) is generally due within 120 days of receiving the initial decision. Commercial plans set their own limits, which are listed in your contract or provider manual.
Can I bill the patient if insurance denies the claim?
Sometimes. If you're in network, your contract often blocks billing the patient for denials caused by practice errors, like missing authorization. Check the denial reason and your contract before sending a patient bill.
This guide is general information, not legal or billing advice for your specific situation. Payer rules change, so confirm requirements with each insurer.