CO-29 denial code: the time limit for filing has expired

Claim adjustment reason code 29 says: the time limit for filing has expired. The payer received the claim after its deadline for that date of service, and won't pay it.

With group code CO, the patient can't be billed. For most practices, CO-29 is money lost for good, which is why it is worth more attention than its volume suggests.

• Medicare: a claim must be filed within 12 months (one calendar year) of the date of service.
• Commercial and Medicaid plans: each sets its own limit in its contract or provider manual. Many are shorter than Medicare's, sometimes 90 days.
• Corrected claims and secondary claims often have their own deadlines, counted from the date of the first payer's decision.

A claim counts as filed when the payer accepts it. A claim the clearinghouse or payer rejected for a formatting error was never received, however early it was sent.

• The claim was rejected and nobody noticed, so it was never actually filed.
• It went to the wrong payer first (see CO-109) and reached the right one too late.
• It waited on a missing approval, note or charge until the deadline passed.
• A secondary claim was never sent after the primary payer paid.
• The practice was using Medicare's deadline for a plan with a shorter one.

• You can prove it was filed on time: a payer acceptance report or claim acknowledgement dated within the limit. Rejection notices don't count.
• Medicare recognises a few exceptions, such as an administrative error by Medicare or its contractor, or Medicare coverage granted to the patient retroactively.
• The payer's own delay caused it, for example a corrected claim requested after the deadline.

Without proof like this, an appeal rarely succeeds.

• Track every claim to acceptance, not just to "sent". Work rejections the same day.
• Know each payer's limit and count it from the date of service.
• Don't hold claims waiting on paperwork without a deadline in view.
• Send secondary claims as soon as the primary payer's answer arrives.

CO-29 is a deadline problem, so it is watched at billing and after.

Claira Health's AI agents catch this before the claim goes out, and tell your biller what's wrong in plain English. Your team sees only what needs a decision, and approves every step. On a 20-minute call, we’ll walk through it using one of your own denials.

How many of your claims are one rejection away from CO-29? Book a 20-minute call.