Denial code appeal templates

What each denial code means, whether to appeal or send a corrected claim, what to attach, and a letter template you can copy.

CO-4Modifier missing, invalid, or inconsistent with the procedure.Fix guide & template → CO-11The ICD-10 code doesn't support the CPT code billed.Fix guide & template → CO-16Missing or invalid data on the claim — usually fixable by resubmission.Fix guide & template → CO-18Payer thinks this service was already billed.Fix guide & template → CO-22Payer thinks another plan should pay first.Fix guide & template → CO-29Payer says the claim arrived after the filing deadline.Fix guide & template → CO-50Payer says the service wasn't medically necessary.Fix guide & template → CO-97Payer bundled this service into another one.Fix guide & template → CO-197Payer has no prior authorization on file.Fix guide & template →

Stop writing these off — get a free denial audit

Send us 100 denied claims. We'll show you what's recoverable and draft the appeals for your team to approve.

Get a free denial audit See the agents work