CO-29: Time limit for filing has expired

What it means

CO-29 means the claim arrived after the payer's timely filing window measured from the date of service. The service may be perfectly valid, but the filing clock ran out. As a CO code the balance is contractual and cannot be billed to the patient.

Mechanically this is a date comparison between the date of service and the receipt date against the payer's filing limit. Timely filing can sometimes be overturned with proof of timely original submission, so documentation of the first attempt is often the only path to payment.

Why it happens in behavioral health

Timely filing hits behavioral health hard because episodes are long and authorizations are complex. Residential and PHP claims can stall while a program waits on authorization, concurrent review, or corrected demographic data, and the filing clock keeps running the whole time. By the time billing is clean the window may have closed.

SUD programs also lose claims to timely filing when a client's coverage is discovered late or COB delays push submission past the limit. Track filing deadlines from the date of service, not from when billing is ready, and escalate stalled authorizations before the window closes.

How to fix it

• Check the payer's exact filing limit and confirm the claim truly missed it.
• Gather proof of any timely original submission such as clearinghouse acceptance reports.
• File an appeal with that proof if you submitted or attempted submission on time.
• If a prior payer's delay caused the lateness, include the primary EOB dates to support an exception.

How to prevent it

• Track filing deadlines from date of service across long episodes, not from billing-ready date.
• Escalate stalled authorizations and concurrent reviews before the filing window closes.
• Keep clearinghouse acceptance records so timely submission can be proven on appeal.

Related denial codes