CO-29 denial: Timely filing expired
The payer says the claim reached it after the filing deadline.
Common causes
- The claim was submitted late
- An earlier submission was rejected and never fixed
- The practice did not track filing limits for each payer
How to fix it
- Gather proof of timely filing, such as a clearinghouse acceptance report or earlier payer response
- Appeal with that proof, following the payer's appeal process
- If no proof exists, ask your billing lead whether any adjustment is allowed under your contract
How to prevent it
- Track filing limits by payer; Medicare generally allows 12 months from the date of service, and other payers vary
- Work rejections the same day so claims are not lost
Zenith billers and AR specialists work denials like this inside your practice-management system, and your practice stays the billing provider. See AR follow-up and medical billing.
Educational summary, not billing or legal advice. Payer rules and deadlines vary; always check the payer’s own policy and the remark code on your remittance.