Medical Insurance Claim Filing Time Limits | Avoid CO-29 Denials

Every medical practice has experienced it at least once. A claim goes out late. The denial comes back with code CO-29. And unlike almost every other denial in medical billing, there is nothing you can do about it. The revenue is gone.

Medical insurance claim filing time limits are the deadlines payers set for claim submission after the date of service. Miss the deadline and no correction, appeal, or resubmission will recover that payment.

Understanding these limits, by payer, by plan type, and by state, is one of the most straightforward ways a practice can protect its revenue. GenMediTech’s Denial Management and AR Services help practices track filing deadlines and recover revenue before windows close.

This guide covers every major payer’s timely filing deadline, what happens when you miss one, when appeals are possible, and exactly how to make sure your billing team never loses revenue to a CO-29 denial again.

What Are Medical Insurance Claim Filing Time Limits?

A timely filing limit in medical billing is the maximum number of days a provider has to submit a claim to an insurance payer after the date of service. Each payer sets its own deadline. Some are defined by federal regulation. Others are written into your provider contract.

The clock starts on the date of service, not the date you received the patient’s insurance information, not the date the patient paid their co-pay, and not the date you finished your documentation.

Why Timely Filing Limits Exist?

Payers use timely filing limits to manage their claims processing workload and prevent fraudulent backdated claims. From a compliance standpoint, CMS established Medicare’s timely filing rule under federal regulation 42 CFR 424.44, requiring claims to be submitted within 12 months of the date of service.

How Timely Filing Limits Differ from Claim Processing Timelines?

A timely filing limit is about when you submit the claim. A claim processing timeline is about how long the payer takes to pay after receiving it. These are two separate things. A claim submitted on day 89 of a 90-day window is filed on time, but it still takes 14 to 30 days for the payer to process and pay.

Medical Insurance Claim Filing Time Limits by Payer | 2026 Complete Table

This is the complete timely filing limits by payer reference table every billing team needs posted at their workstation.

Important note: Commercial payer limits listed here are general standards. Your actual deadline is what is written in your provider contract with that payer. Always verify against the contract before assuming a standard limit applies.

Why Auto Insurance and No-Fault Have the Strictest Deadlines

Auto insurance and no-fault claims fall under state tort law, not federal healthcare regulation. States like New York require no-fault medical claims within 45 days of the date of service. Florida allows 35 days in most cases.

Missing these windows is especially costly because the services involved, emergency care, trauma treatment, physical therapy, are often high value.

How to Find Your Exact Timely Filing Limit for a Specific Payer

For Medicare: the medical insurance claim filing time limit is exactly 12 months from the date of service, no exceptions without documented good cause.

For Medicaid: contact your state Medicaid agency or check the state’s provider manual. Every state is different.

For commercial payers: open your provider contract and search for “timely filing” or “claim submission deadline.” If you do not have a signed contract with a commercial payer, call their provider relations line and get the limit in writing.

What Happens When You Miss a Medical Insurance Claim Filing Time Limits Deadline?

This is where CO-29 comes in. CO-29 is the Claim Adjustment Reason Code for “the time limit for filing has expired.” When this code appears on an ERA or EOB, the payer is telling you one thing, they received the claim after their deadline and will not pay it.

Why Is CO-29 Different from Every Other Denial Code?

Most denial codes are fixable. CO-4, wrong modifier, fix the modifier and resubmit. CO-16, missing information, add the information and resubmit. CO-11, wrong diagnosis, correct the code and resubmit.

CO-29 is not fixable through resubmission. A timely filing denial is permanent, unlike almost every other denial type in medical billing The window is closed.

You cannot correct the date the claim was submitted. The only options are a timely filing appeal, which requires specific documented exceptions, or writing off the balance.

Can You Write Off Timely Filing Denials?

For Medicare and Medicaid patients, providers generally cannot bill the patient for a service that was denied due to provider error, and late filing is considered provider error. The balance gets written off as a provider adjustment. The practice absorbs the loss entirely.

For commercial payer patients, whether you can bill the patient depends on your contract and state law. In most cases the answer is no, especially if the contract requires you to file within the stated window as a condition of reimbursement.

Can You Appeal a Timely Filing Denial?

In most cases, no. But there are documented exceptions where a timely filing appeal can succeed.

When Timely Filing Appeals Are Allowed?

Medicare allows late filing exceptions for documented good cause under 42 CFR 424.44(b). Accepted exceptions include:

• A federal or state-declared natural disaster prevented timely filing
• The patient’s eligibility was retroactively established after the normal filing deadline
• A Medicare Secondary Payer situation was not identified until after the primary payer processed the claim
• A system error on the provider’s EHR or clearinghouse caused the claim to be held without the provider’s knowledge

Commercial payers rarely grant timely filing appeals. When they do, the provider must show documented proof that the delay was caused by circumstances beyond their control, payer system errors, retroactive insurance changes, or coordination of benefits complications.

What Documentation You Need for a Timely Filing Appeal?

A successful appeal requires more than a letter asking for an exception. It needs:

• The original claim with date of service
• Proof of the initial submission attempt, clearinghouse confirmation, rejection notice, or system log
• A written explanation of why the claim was late
• Supporting documentation for the exception being claimed, disaster declaration, retroactive eligibility notice, or payer system error confirmation

How to Write a Timely Filing Appeal Letter That Works?

Keep it specific. State the claim details, the denial date, the reason the claim was filed late, and the specific exception that applies. Attach every supporting document. Vague appeal letters that say “we were unaware of the deadline” do not work. Appeals that document a specific qualifying exception with proof have a real chance.

Most Common Reasons Practices Miss Timely Filing Deadlines

Understanding why these denials happen is the first step in preventing them.

• Charge capture gaps: A patient was seen, treated, and discharged. The encounter never made it into the billing system. By the time someone notices, the filing window has closed.
• Claims held for documentation: A claim is generated but held because a physician’s signature is missing or additional records are needed. Weeks pass. The documentation arrives. But nobody checks whether the filing deadline has passed.
• Unworked eligibility denials: A claim comes back with an eligibility rejection. It sits in a work queue. By the time someone fixes the patient’s insurance information and resubmits, the timely filing window is gone.
• Billing company transitions: This is one of the most underreported causes of timely filing losses. When a practice switches billing companies, claims in progress fall through the handoff. Neither team realizes specific claims were never submitted until the denial comes back months later.
• Staff turnover: A billing team member leaves mid-cycle. Their work queue is not properly reassigned. Claims sit untouched until someone new discovers them, often after the deadline.

How to Track Timely Filing Deadlines Across Multiple Payers

Prevention is the only real solution for timely filing denials. Here is how billing teams do it effectively.

• Build a payer-specific filing deadline calendar. Note each payer’s claim submission deadline alongside their name. List every payer you work with and their timely filing limit. Update it when contracts renew. Post it where your billing team can see it daily.
• Set internal deadlines earlier than payer deadlines. If UnitedHealthcare allows 90 days, your internal target should be 60 days. Build in buffer for corrections, documentation delays, and system issues.
• Run a weekly AR aging report filtered by filing risk. Any claim that has not been submitted or resolved at 60 percent of its timely filing window needs immediate attention. For a 90-day payer, that is day 54. For a 180-day payer, that is day 108.
• Flag held claims for 30 days. Any claim held for documentation or additional information for more than 30 days should trigger an alert. Someone needs to either get the documentation or make a decision about submitting what is available.
• Use your RCM or practice management system’s timely filing alerts. Most modern systems can flag approaching deadlines automatically. If your system has this feature and you are not using it, turn it on today.

How to Avoid CO-29 Denials? Practical Steps for Your Billing Team

These are the steps that actually prevent timely filing losses.

• Submit claims within 48 hours of the date of service. The longer a claim sits, the higher the chance it gets lost.
• Verify timely filing limits before seeing your first patient under any new payer contract. Write it down and put it in your system.
• Reconcile your appointment schedule against submitted claims every week. If a patient was seen and no claim exists, find out why immediately.
• Track CO-29 denials separately. If they are trending up, a workflow problem is getting worse, not better.
• After any billing system migration or company switch, audit all open claims from the past 90 days yourself. Never assume the previous team finished everything.

Timely Filing Limits for Medicare — A Closer Look

Medicare deserves its own section because it is the highest-volume payer for most US practices and its timely filing rule is the most clearly defined.

Under 42 CFR 424.44, Medicare requires claims to be filed within one calendar year, 12 months, from the date of service. This applies to Part A, Part B, and most Medicare Advantage plans, though Medicare Advantage plans may have their own additional requirements defined in their contracts.

Medicare Timely Filing Exceptions

CMS allows late filing in documented good cause situations. The specific exceptions are:

• Administrative error by CMS or its contractors that prevented timely filing
• Retroactive Medicare entitlement, the patient was enrolled in Medicare retroactively after the service was provided
• Medicare Secondary Payer situations where another payer was primary and the provider did not know Medicare was involved until later
• Presidentially declared disasters affecting the provider’s ability to file

These exceptions require formal documentation submitted to the Medicare Administrative Contractor for your jurisdiction. They are not automatic, you must apply and provide proof.

Medicare Secondary Payer and Timely Filing

When Medicare is secondary to another payer, the timely filing clock starts differently. The 12-month window runs from the date of the primary payer’s EOB, not the date of service. This is one of the most misunderstood aspects of Medicare timely filing and one of the most common sources of avoidable CO-29 denials.

2026 Updates Affecting Claim Filing Deadlines

CMS Prior Authorization Final Rule, effective January 2026

This rule requires Medicare Advantage and Medicaid managed care plans to issue prior authorization decisions within 72 hours for urgent requests and 7 calendar days for standard requests. 

Faster authorization decisions mean faster service delivery, and that means the timely filing clock on authorized procedures starts sooner. Practices need workflows that submit claims promptly after authorization is granted.

State Medicaid timely filing updates

Several high-population states updated their Medicaid timely filing rules in 2024 and 2025. California extended certain Medicaid timely filing windows under Medi-Cal to 12 months. Texas Medicaid maintains a 95-day limit from date of service for most claims. 

New York Medicaid allows 90 days. Florida Medicaid requires submission within 12 months for most fee-for-service claims. Always verify against the current state provider manual, these rules change.

Clearinghouse technology improvements

Leading clearinghouses now offer automated timely filing tracking that flags claims approaching their deadline in real time. If your clearinghouse offers this feature, activate it. It is one of the most cost-effective denial prevention tools available.

Conclusion

Timely filing denials are the only denial in medical billing with no recovery path. Knowing the medical insurance claim filing time limits for every payer in your mix is not optional, it is a basic revenue protection requirement.

CO-29 means the window is closed and the revenue is gone. There is no appeal process for most cases, no resubmission option, and in most situations no ability to bill the patient.

The good news is that timely filing denials are also among the most preventable denials in the revenue cycle. Submit claims quickly. Track deadlines by payer. Set internal targets earlier than payer limits. Audit your AR weekly for claims approaching their window.

Practices that treat timely filing as a revenue protection priority, not just a billing department task, consistently maintain CO-29 denial rates near zero. That is money that stays in your practice instead of being written off.

If your practice is losing revenue to timely filing denials or wants a structured review of your current billing workflows, GenMediTech offers a free billing audit that identifies exactly where claims are falling through, before the deadlines pass.

Frequently Asked Questions

What are medical insurance claim filing time limits?

A timely filing limit is the deadline a provider has to submit a claim to an insurance payer after the date of service. Each payer sets its own deadline, Medicare requires 12 months by federal regulation, while commercial payers typically allow 90 to 180 days depending on the provider contract.

What is the denial code CO-29? 

CO-29 is the Claim Adjustment Reason Code for timely filing limits exceeded. It means the claim was submitted after the payer’s deadline. Unlike most denial codes, CO-29 cannot be corrected and resubmitted. The revenue is permanently lost unless a documented good cause exception applies.

What is Medicare’s timely filing limit? 

Medicare requires claims to be filed within 12 months, one calendar year, from the date of service. This is set by federal regulation under 42 CFR 424.44. For Medicare Secondary Payer situations, the 12-month window runs from the date of the primary payer’s EOB rather than the date of service.

Can you appeal a CO-29 timely filing denial? 

In limited circumstances, yes. Medicare accepts late filing appeals for documented good cause including retroactive eligibility, Medicare Secondary Payer situations, CMS administrative errors, and presidentially declared disasters. Commercial payer timely filing appeals rarely succeed without documented proof that the delay was caused by factors outside the provider’s control.

Which insurance payer has the shortest claim filing deadline? 

Auto insurance and no-fault claims typically carry the strictest filing windows, 30 to 90 days depending on state law. New York no-fault requires submission within 45 days of service in most cases. These are significantly shorter than Medicare and most commercial payers.

How do I find the timely filing limit for a specific insurance payer? 

For Medicare, it is 12 months by federal law. For Medicaid, check your state’s provider manual. For commercial payers, review your provider contract directly. The timely filing limit is written into the agreement. If you do not have a contract, call the payer’s provider relations line and request the limit in writing.

What happens if a claim is denied for timely filing and I cannot appeal? 

For Medicare and Medicaid patients, providers generally cannot bill the patient for a denial caused by a provider error — and late filing is considered provider error. The balance is written off as a provider adjustment. For commercial payer patients, whether you can bill the patient depends on your contract terms and state law. In most cases the provider absorbs the loss.

How can practices prevent CO-29 denials? 

Submit claims within 48 hours of the date of service wherever possible. Set internal submission deadlines earlier than payer limits. Run weekly AR aging reports to flag claims approaching their deadline. Reconcile appointment schedules against submitted claims weekly. Track CO-29 denials separately to identify workflow patterns causing late submissions.