Timely Filing Limit
A timely filing limit is the payer's deadline for submitting a claim, counted from the date of service. Medicare allows 12 months; many commercial payers allow only 90 to 180 days for in-network providers. Claims filed late are denied (CO-29) and the balance usually cannot be billed to the patient.
- Medicare
- 12 months from date of service
- Commercial (typical)
- 90–180 days, per contract
- Denial code
- CO-29
- Bill the patient?
- No — provider liability in-network
How does a timely filing limit work?
Every payer gives you a fixed window, counted from the date of service, to get the claim into their system. Miss it and the claim denies with CO-29 ("the time limit for filing has expired"), and because the CO group code means contractual obligation, the balance becomes your write-off, not the patient's bill.
The date that matters is the date the payer receives the claim, not the date you created or transmitted it. A claim that bounces at the clearinghouse for a bad member ID and sits unworked for four months has not been "filed" in any way the payer recognizes.
What are the most common timely filing limits?
Medicare is generous at 12 months. Commercial payers are not, and the limit in your contract can be shorter than the payer's published default:
| Payer | Typical limit (participating) |
|---|---|
| Medicare | 12 months from date of service |
| UnitedHealthcare | 90 days (many plans) |
| Cigna | 90 days |
| Aetna | 120 days |
| BCBS plans | Varies by state, commonly 180–365 days |
| Medicaid | Varies by state, commonly 90–365 days |
Always verify against your own contract and the current payer manual. The timely filing limits lookup tool maintains the current windows by payer, including secondary and corrected-claim rules.
How do you prove a claim was filed on time?
With the payer's own acknowledgment, nothing less. When you appeal a CO-29, attach the 999/277CA acceptance report or the clearinghouse report showing the payer accepted the claim, with the claim number and received date visible. Payer reps are trained to dismiss internal billing-system screenshots, so lead with the electronic acknowledgment and reference the original claim number (DCN/ICN) if one exists.
Example of what is at stake: a three-provider practice discovers 62 UnitedHealthcare claims from a credentialing gap were held 95 days and denied CO-29. Average billed value $142, average allowed roughly $95. That is about $5,900 in allowed revenue riding on whether the biller can produce acceptance reports showing an earlier rejected submission inside the 90-day window. With proof, most of it comes back on appeal; without it, the whole batch is a write-off.
What are the exceptions to timely filing?
Payers recognize a short list of good-cause exceptions, and you must document them:
- Retroactive eligibility: the patient's coverage (or Medicare entitlement) was granted retroactively after the date of service.
- Coordination of benefits delays: you filed the primary on time and the secondary window runs from the primary EOB date. Attach the primary remittance; see coordination of benefits.
- Payer or government error: misinformation from the payer, or claims misrouted by the payer's own system.
- Disaster or system outage: declared emergencies and documented clearinghouse outages, with the incident reference number.
Frequently asked questions
12 calendar months (1 full calendar year) from the date of service, set by federal law under the Affordable Care Act. Claims received later are denied and the denial cannot be appealed on the merits, only on the narrow exceptions CMS allows, such as retroactive Medicare entitlement or an administrative error by Medicare itself.
No. The clock runs from the date of service, not from your last submission. Corrected claims and resubmissions must still land inside the original window unless the payer contract specifically allows a resubmission window (many allow 180 days from the original denial for corrected claims, but only if the first claim was filed on time).
Not if you are in-network. Nearly every participating provider agreement makes timely filing denials provider liability, so the balance is written off. Billing the patient anyway violates the contract and, for Medicare and Medicaid, can create compliance exposure.
The strongest proof is the payer's own acceptance report: a 277CA claim acknowledgment or clearinghouse acceptance report showing the payer received the claim on a specific date. A screenshot of your billing software showing a submission date is weak evidence; most payers reject it on appeal.
Sources & further reading
Reviewed by the ImmediCare Solutions RCM team
Certified billers and coders handling claims across 50+ specialties nationwide. This entry is reviewed against current payer policy and CMS rules. Last review: Jul 5, 2026.
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