At the end of a fiscal year, a three-location urgent care group asked us to explain a write-off line that had grown to a little over $38,000. Every dollar of it carried the same adjustment reason: CO-29, the time limit for filing has expired. When we pulled the claims, the story was the same one we always find. Two thirds had been rejected at the clearinghouse for small data errors and never resubmitted. The rest had gone out on time to the wrong payer, come back with CO-22 (other coverage primary), and sat in a queue until the right payer's clock ran out. Not one of those services was unpayable on the day it was rendered.
Timely filing is the deadline nobody argues with. A payer that denies for medical necessity can be persuaded with records. A payer that denies for timely filing wants one thing, proof that the claim was received in time, and if the practice does not have it, the money is gone. Under Medicare rules and almost every commercial contract, the patient cannot be billed for it either. This article is the reference we wish every billing desk had taped to the wall, plus the tracking system that makes the reference unnecessary most days.
A timely filing limit is the maximum time a payer allows between the date of service and the date it receives the claim. Original Medicare allows 12 months from the date of service. State Medicaid programs set their own limits, from 90 days to a year. Commercial payers set theirs by contract, commonly 90 to 180 days for in-network providers and sometimes longer for out-of-network claims. Secondary claims usually run from the date of the primary payer's remittance. The limit is about receipt by the payer, not the date your system says it sent the claim, and a claim rejected before adjudication was never received.
How timely filing is counted
Four rules decide whether a claim is on time, and every one of them has tripped a practice we have worked with. First, the clock starts on the date of service, or for claims with a span of dates, the "through" date. Medicare uses the through date for institutional claims and the date of service for professional lines. Second, the clock stops when the payer receives the claim, which for electronic claims means the payer's acceptance on the 277CA, not the day it left the practice management system. A claim rejected at the clearinghouse or at the payer's front end has no receipt date. Third, for a secondary claim, most payers count from the date on the primary payer's remittance, because the claim could not have been filed before the primary adjudicated; Medicare as a secondary payer still applies its 12-month limit from the date of service regardless. Fourth, a corrected claim is usually treated as a new submission for timely filing purposes unless the payer's manual says corrections relate back to the original, so corrections must be made inside the original window or inside a separate corrected-claim window the payer publishes.
The appeal deadline is a different clock entirely. It runs from the denial date and is set by the payer's appeal policy. A claim can be inside the appeal window and outside the filing window at the same time, which is exactly the situation that produces an unwinnable appeal.
Timely filing limits by payer: the reference table
The limits below are the published defaults in each payer's rules or provider manual. For commercial payers, your contract overrides the manual, so read the claims section of your agreement first. Payers change these limits; the "where to verify" column is where to check the current value before relying on the table.
| Payer | Typical limit | Counted from | Where to verify | Notes |
|---|---|---|---|---|
| Original Medicare (Part B professional) | 12 months (one calendar year) | Date of service | Medicare Claims Processing Manual, Chapter 1, Section 70; your MAC's website | Set by federal law; exceptions only for Medicare administrative error, retroactive entitlement, and retroactive disenrollment from a Medicare Advantage plan |
| Medicare Advantage, contracted provider | Per contract, commonly 90 to 180 days | Date of service | Your participation agreement; plan provider manual | The contract controls; some plans grant a year, many do not |
| Medicare Advantage, non-contracted provider | Commonly 12 months | Date of service | Plan provider manual (UnitedHealthcare, for example, publishes 365 days for non-contracted Medicare Advantage claims) | Plans tend to mirror Original Medicare for non-contracted claims, but confirm per plan |
| Medicaid fee-for-service: Texas | 95 days | Date of service | Texas Medicaid Provider Procedures Manual on the TMHP site | Deadline falling on a weekend or holiday moves to the next business day |
| Medicaid fee-for-service: Illinois | 180 days | Date of service | Illinois HFS provider handbooks | Applies to initial and resubmitted claims when HFS is primary |
| Medicaid fee-for-service: Washington (Apple Health) | 365 days | Date of service | Washington Health Care Authority billing guides | Initial claims; resubmissions have their own rules in the ProviderOne billing guide |
| Medicaid fee-for-service: California (Medi-Cal) | Six months following the month of service for full payment | End of the month of service | Medi-Cal provider manual, claim submission and timeliness section | Late claims are paid at reduced rates up to one year, then denied; delay reason codes allow exceptions |
| Medicaid fee-for-service: New York | 90 days | Date of service | eMedNY provider manuals, general billing section | Late submission allowed only with a documented delay reason |
| Medicaid fee-for-service: Florida and Ohio | 12 months | Date of service | Each state agency's provider handbook | Among the more generous programs; managed care plans in these states may use shorter limits |
| Medicaid managed care plans (all states) | Per plan, often 90 to 180 days | Date of service | Plan provider manual; state contract requirements | Can be shorter than the state fee-for-service limit; check each plan separately |
| UnitedHealthcare commercial | 90 days in network unless the contract says otherwise; 180 days out of network | Date of service | UnitedHealthcare Administrative Guide | Many contracts negotiate longer; the guide defers to the agreement |
| Aetna commercial | 120 days is the common default; ranges from 90 to 365 by plan and contract | Date of service | Aetna provider manual and your agreement | Medicaid and Medicare Advantage lines of business differ |
| Cigna commercial | 90 days in network; 180 days out of network | Date of service | Cigna "When to File" reimbursement policy | Contract may extend the in-network window |
| Humana | Per contract; Medicare Advantage non-contracted 365 days | Date of service | Humana provider manual by line of business | Humana does not publish one limit; commercial, Medicaid and Medicare lines differ |
| Blue Cross Blue Shield plans | Varies by plan, commonly 90 to 365 days | Date of service | Your local plan's provider manual; the home plan's rules apply on BlueCard claims | Each of the independent plans sets its own limit |
| TRICARE | One year | Date of service, or discharge for inpatient care | TRICARE regional contractor's provider handbook | Exceptions require a written waiver request with documentation |
| VA Community Care Network | 180 days | Date of service | VA Community Care provider pages and the regional network administrator | Applies to authorized care; unauthorized emergency care has separate rules |
| Workers' compensation | Set by state law; varies widely | Date of service | State workers' compensation board fee schedule and billing rules | Some states have very short windows; employer and carrier information must be correct on the first claim |
| Secondary claims (any payer) | Commonly 60 to 180 days | Date of the primary payer's remittance | Secondary payer's provider manual | Medicare secondary claims still run 12 months from the date of service |
Notes on the rows that cause the most trouble
Medicare: the one limit that is written into law
The 12-month Medicare limit comes from Section 6404 of the Affordable Care Act and is written into the Medicare Claims Processing Manual, Chapter 1, Section 70. It is the same for every Medicare Administrative Contractor and there is no contract to negotiate. The exceptions are narrow and specific: an error by Medicare or its contractor that caused the delay, a beneficiary whose Medicare entitlement was made retroactive, a dually eligible patient whose Medicaid agency recouped payment after Medicare entitlement was granted retroactively, and a beneficiary retroactively disenrolled from a Medicare Advantage plan. "We didn't know the patient had Medicare" is not an exception. The practice is expected to have verified eligibility.
Medicaid: fifty programs, fifty rules
The Medicaid rows above are examples, not a complete list, and every one of them can change when a state revises its provider manual. Texas at 95 days and New York at 90 days are among the shortest in the country; a claim rejected twice at the clearinghouse can run out of time there in a single billing cycle. Medi-Cal is unusual in paying late claims at a reduced rate rather than denying them outright, which means a late Medi-Cal claim is still worth filing. Medicaid managed care plans frequently set shorter limits than the state program, so a practice in a state with a 365-day fee-for-service limit can still face a 90-day plan limit. If your state is not in the table, your state Medicaid agency's provider manual has a claim submission chapter, and the limit is in it.
Commercial payers: the contract beats the manual
The commercial rows show the payers' published defaults. The number that applies to you is in the claims submission section of your participation agreement, and it may be longer or shorter. We have seen agreements with 60-day limits for specific product lines and agreements with a year. When a contract is silent, the provider manual applies, and when state prompt-pay or timely filing law sets a minimum, the law applies. Out-of-network claims often get a longer window because the plan has no contract to point to, but the plan's member agreement may still set one. Check the contract rate benchmark notes for your payer while you have the contract open; the timely filing clause and the fee schedule are usually a few pages apart.
What counts as proof of timely filing
When a payer denies CO-29 and the practice believes the claim was filed on time, the appeal lives or dies on documentation. What works: the clearinghouse report showing the payer's acceptance of that specific claim with the date and the payer's claim control number (the 277CA with an A1 or A2 status), the payer portal's submission history, a certified mail receipt for a paper claim, a fax confirmation page that shows the claim pages, or the primary payer's remittance for a secondary claim showing the date the secondary clock started. What does not work: a screenshot of the practice management system showing a "sent" status, a batch report that shows the file left but not that the claim was accepted, or a staff member's note that says "resubmitted". Save the 277CA for every batch, every day, in a folder by submission date. It costs nothing and it is the only evidence most payers accept.
How to build the tracking system
The practices that never see CO-29 do not have better memories. They have a system with six parts, and most of it already exists in the practice management software if someone turns it on.
- A payer master table. One row per payer and line of business with the filing limit, the counted-from rule, the corrected-claim rule, the secondary rule, the appeal window and the source document with its date. Review it twice a year and whenever a contract renews. Most practice management systems have a field for this on the payer record; fill it in so the system can calculate deadlines.
- A daily rejection routine. Someone opens the clearinghouse every morning, works every rejection from the prior day, resubmits the same day, and confirms acceptance the next morning. Rejections are the largest single source of timely filing losses because a rejected claim looks "sent" in every report except the one nobody reads.
- A "no response" report at 30 days. Every claim with no 277CA acceptance or no remittance 30 days after submission gets a status check by portal or by the 276/277 transaction. "Not on file" means resubmit today.
- An at-risk report by days to deadline. Sort open claims by date of service, calculate days remaining against the payer master table, and work anything inside 45 days of its limit first, regardless of dollar amount. This report should be short; if it is long, the daily routine upstream is failing.
- A secondary claim trigger. When a primary remittance posts with a balance and the patient has secondary coverage, the secondary claim goes out within a week, automatically where the system supports it. Secondary claims are the second-largest source of CO-29 we see, because they wait for someone to notice.
- A monthly CO-29 review. Every timely filing write-off is listed by payer, date of service, dollar amount and the reason it was late, and the manager signs the list. The reasons feed back into the first five steps. The goal is a blank page.
Step six is the measure. A practice that writes off any timely filing dollars at all has a process gap, and the write-off log tells you exactly where. The denial codes tool lists CO-29 with the first action for each situation, and our medical billing service runs this exact system for the practices we bill for.
What to do when a deadline has already passed
Start with the evidence. If the claim was accepted in time and the payer's records are wrong, appeal with the acceptance report; these appeals are won routinely because the proof is unambiguous. If the claim was late because of the payer's own error, a wrong eligibility response, a misdirected claim the payer should have forwarded, or a retroactive eligibility change, appeal with the documentation and cite the payer's policy on exceptions; Medicare's exceptions are in the Claims Processing Manual and most commercial manuals have a similar list. If the claim was late because of the practice's own delay, be honest about the odds: most payers will not reconsider, though some commercial plans allow a one-time reconsideration for a documented system failure, and Medi-Cal's reduced-payment rule means a late claim can still bring in something.
What a practice cannot do is move the balance to the patient. Medicare prohibits billing the beneficiary for a claim denied for untimely filing, and nearly every commercial participation agreement includes the same hold-harmless language. A timely filing write-off is the practice's loss by design, which is the whole argument for the tracking system above. If the write-offs are large, the question is not how to appeal them but where the process broke, and that is the kind of question an RCM audit is built to answer.
Questions we hear
Does the timely filing limit run from the date of service or the date the claim was sent?
From the date of service (or the through date for a span of dates) to the date the payer receives the claim. The date your system sent it is irrelevant unless the payer accepted it. A claim rejected by the clearinghouse or by the payer's front-end edits does not count as received, which is why rejected claims are the biggest source of timely filing denials.
What is the timely filing limit for Medicare?
Twelve months from the date of service, for every Medicare Administrative Contractor, with no contract variation. The limited exceptions are Medicare's own administrative error, retroactive Medicare entitlement, a related Medicaid recoupment after retroactive entitlement, and retroactive disenrollment from a Medicare Advantage plan. Medicare Advantage plans set their own limits, by contract for participating providers and by plan policy for non-contracted ones.
Can we bill the patient when a claim is denied for timely filing?
Almost never. Medicare prohibits it for assigned claims, and standard participation agreements with commercial payers and Medicaid plans include hold-harmless clauses that forbid billing the member for the practice's filing failures. A CO group code on the denial (contractual obligation) signals this. The only common situation where a patient can be billed is an out-of-network claim with no contract and no state law to the contrary, and even then the practice's financial policy and the patient's reasonable expectations should be considered first.
How is the limit counted for a secondary claim?
Most payers count secondary claims from the date of the primary payer's remittance, because the secondary claim cannot be filed until the primary has adjudicated. The exact window is in the secondary payer's manual and is often shorter than the primary limit. Medicare as a secondary payer is the exception: its 12-month limit runs from the date of service regardless of when the primary paid, so a slow primary payer can consume most of Medicare's window.
Does a corrected claim get a new timely filing window?
Usually not. Most payers treat a corrected claim (frequency code 7) as a new submission that must itself arrive inside the original filing limit, and some publish a separate, shorter window for corrections measured from the original remittance. A few payers relate corrections back to the original receipt date. Because the rules differ, the corrected-claim rule belongs in your payer master table next to the filing limit, and corrections should go out the same week the error is found.
Sources and references
- Medicare Claims Processing Manual (Publication 100-04), CMS: Chapter 1, Section 70 sets out the 12-month filing limit, how the date of service is determined and the exceptions.
- Original Medicare (Fee-for-Service) Appeals, CMS: the appeal levels and the good cause for late filing rules that apply when an appeal, not a claim, is late.
- Medicare Managed Care Appeals & Grievances, CMS: how Medicare Advantage plans must handle claim disputes, including from non-contracted providers.
- Coordination of Benefits & Recovery Overview, CMS: how Medicare determines primary and secondary payer status, which decides whose filing clock applies to a crossover claim.
- Welcome Texas Medicaid Providers, Texas Medicaid & Healthcare Partnership: the Texas Medicaid Provider Procedures Manual, including the 95-day claim filing deadline and its exceptions.
- Medical Providers, Illinois Department of Healthcare and Family Services: provider handbooks and notices, including the 180-day timely filing requirement.
- Billers, providers, and partners, Washington State Health Care Authority: Apple Health billing guides and ProviderOne resources, including the 365-day initial claim limit.
