Why was my claim denied? Common reasons and fixes
Most claim denials come from a handful of fixable issues — coding errors, missing referrals, or eligibility problems. Here's how to spot and resolve each.
Claim denials feel personal, but most are mechanical: wrong code, missing paperwork, or a timing issue. Before you appeal, find out which category your denial falls into — many can be fixed by the provider's billing team in a single phone call.
The top denial reasons
- Coding errors — Wrong CPT or ICD-10 code. The provider's billing office can resubmit with corrected codes.
- Missing prior authorization — Some services (MRIs, certain surgeries, specialty drugs) need authorization before the visit. Without it, the claim is denied.
- Out-of-network provider — The claim was processed but paid at the lower out-of-network rate, or denied entirely on an HMO/EPO plan.
- Not medically necessary — The insurer's clinical reviewer didn't agree the service was needed. This is the most common denial reason for major procedures.
- Coordination of benefits — You have two insurance plans and the wrong one was billed first.
- Eligibility — The patient wasn't enrolled on the date of service, or coverage had been terminated.
- Untimely filing — The provider waited too long to submit the claim.
What to do, by type
- If it's a coding or billing error
Call the provider's billing department, not the insurer. Ask them to review the claim and resubmit with corrections. This is the fastest fix and resolves the majority of denials.
- If it's a missing prior auth
Ask the provider if they can submit a retro-authorization. Many insurers allow retro auth within 30–60 days, especially if there's a clinical reason it wasn't obtained in advance.
- If it's a medical necessity denial
This is the strongest case for a formal appeal. Get a letter of medical necessity from your provider and follow the appeal process.
- If it's a coordination of benefits issue
Call the insurer and confirm which plan is primary. The 'birthday rule' (whichever parent's birthday is earlier in the year is primary for kids) and tiebreaker rules can get confusing.
- If it's an eligibility denial
Call HR or your benefits administrator to confirm your coverage was active on the date of service. If there was a data error, they can correct it and the claim can be reprocessed.
- If it's untimely filing
The provider eats the cost — federal law prohibits them from billing you for a claim denied solely for the provider's late filing.
FAQ
- How long do I have to dispute a denial?
180 days from the date of the denial to file an internal appeal. After the internal appeal, 4 months for external review.
- Can the provider bill me if my claim is denied?
It depends on the reason. In-network providers usually can't bill you for plan discounts, late filings, or coding errors. They can bill you for non-covered services or amounts above what you owed under your plan.
- What's a 'soft' denial vs. a 'hard' denial?
A soft denial can be fixed by correcting and resubmitting (e.g., wrong code). A hard denial requires a formal appeal (e.g., 'not medically necessary'). The remark code on your EOB tells you which it is.