Every billing team eventually encounters the same quiet catastrophe: a claim that was coded perfectly, documented thoroughly, and submitted in good faith — denied with adjustment code CO-29 because it arrived one day past the payer’s deadline. The service was legitimate. The patient was eligible. But the payer’s clock had already expired, and the entire balance became a contractual write-off.
The problem is rarely carelessness. It is the assumption that “timely filing” means the same thing across every payer. It does not. Anthem, Aetna, Ambetter, Carelon, and GEHA each maintain different deadlines, different starting points, and different rules for corrected claims, secondary claims, and appeals. A billing team that applies a single default deadline to all five payers will lose revenue on at least three of them.
This reference guide breaks down the filing rules for each of these five payers, focusing on the distinctions that actually cause denials: the difference between initial, corrected, and secondary claim deadlines, and the documentation required to prove timely filing when a CO-29 denial is issued.
Why Payer-Specific Filing Rules Matter More Than Ever
Commercial payers have been steadily tightening their filing windows over the past several years. Aetna reduced its non-participating provider window from 27 months to 12 months effective January 1, 2022, and began enforcing that reduction aggressively as claims from early 2022 started reaching the deadline. Anthem’s commercial and Medicare Advantage plans enforce a 90-day window in most states — one of the shortest among major commercial insurers. Ambetter, operating as Centene’s marketplace brand, varies by state — 180 days in most, but as short as 90 days in some markets.
The trend is clear: shorter windows, stricter enforcement, and fewer opportunities to correct late filings. Billing teams that treat timely filing as a single deadline rather than a payer-specific matrix are operating with outdated assumptions.
Anthem (Elevance Health) Timely Filing Limits
Anthem is now part of Elevance Health, though the Anthem, Empire, and Wellpoint brand names remain in active use. The filing rules vary by plan type and state.
Anthem standardized its 90-day commercial and Medicare Advantage window across all Anthem-operated states effective October 1, 2019, cutting what had previously been 365-day windows for many affiliates. Anthem operates in 14 states under different corporate names — California (Anthem Blue Cross), Colorado, Connecticut, Georgia, Indiana, Kentucky, Maine, Missouri, Nevada, New Hampshire, New York (Empire BCBS), Ohio, Virginia, and Wisconsin — but the 90-day standard applies across all of them for commercial and MA professional claims.
Medicaid variations: Anthem’s Medicaid deadlines vary significantly by state. California Medi-Cal allows 180 days for participating providers and 210 days for non-participating providers. Nevada Medicaid allows 180 days for participating providers and 365 days for non-participating providers.
Corrected claims: Anthem generally requires corrected claims to be submitted within the original filing limit, or within the applicable correction window. A corrected claim that is not properly flagged as a correction may be denied as a duplicate.
Secondary claims: When Anthem is the secondary payer, the timely filing clock starts from the primary payer’s Explanation of Payment (EOP) date, not the original date of service. Documentation demonstrating that the claim was submitted to the primary payer within Anthem’s timely filing limit is required.
Aetna Timely Filing Limits
Aetna maintains one of the more complex timely filing structures in commercial insurance. The deadlines vary by network status, plan type, and state law.
The most consequential shift in Aetna’s filing rules was the reduction of the non-participating provider window from 27 months to 12 months, effective January 1, 2022. Practices that historically relied on the extended non-par window now face denials they were not expecting. Aetna began enforcing the new limit aggressively in 2023 as claims from early 2022 started reaching the deadline, and CO-29 denials for non-par claims spiked accordingly.
Corrected claims: Commercial in-network corrected claims are typically due within 90 days of the original ERA/EOB date, though some contracts allow up to 180 days. Aetna Better Health plans generally allow 180 days from the date of service for corrected claims, or 365 days from the Provider Remittance Advice date in some states.
Appeals: Aetna allows 180 days for Level 1 appeals and 60 days for Level 2 appeals. A CO-29 timely filing denial can be appealed, but only with documented proof of timely submission — typically a clearinghouse acceptance report or Availity submission log.
Ambetter Timely Filing Limits
Ambetter is Centene’s health insurance marketplace brand, operating in multiple states. Filing deadlines vary significantly by state, making a single national rule unreliable.
The standard timely filing deadline for initial claims is 180 calendar days from the date of service, or date of primary payment when Ambetter is secondary. However, some states impose shorter deadlines. Texas, for example, enforces a 95-day window through Superior HealthPlan. Ambetter from Absolute Total Care extended its timely filing from 120 business days to 180 calendar days effective July 1, 2024.
Corrected claims: All requests for corrected claims, reconsiderations, or claim disputes must be received within 180 days from the date of the original explanation of payment or denial. Prior processing will be upheld for requests received outside the 180-day timeframe.
Key operational point: Because Ambetter’s deadlines vary so widely by state, billing teams should maintain a state-by-state reference rather than a single default. The difference between 90 days and 180 days is the difference between a claim being paid and a claim being written off.
Carelon Behavioral Health Timely Filing Limits
Carelon Behavioral Health (formerly Beacon Health Options) manages behavioral health benefits for multiple health plans and state programs. There is no single universal Carelon filing limit.
Carelon’s own Out-of-Network Provider Guide sets a default of 90 calendar days from the date of service or discharge, but explicitly states that the default gives way to whatever a specific Provider Manual or state requirement says instead. This is not a suggestion — it is a warning. Billing teams that rely on the 90-day default without verifying the applicable contract may be leaving hundreds of days of filing window unused.
For certain plans, Carelon allows up to 365 calendar days from the date of service or discharge for inpatient admissions. Massachusetts MBHP allows 90 calendar days, Fallon Health allows 120 calendar days, and certain contracts allow 12 months from the date of service if the original claim was filed within 12 months.
Corrected claims: Carelon’s corrected claim window is generally 90 days from the date on the Provider Summary Voucher (PSV) or Explanation of Payment.
Secondary claims: The timely filing limit for secondary claims is 60 days from the date of the other carrier’s EOB, or 12 months from the first date of service, whichever is later.
GEHA Timely Filing Limits
GEHA (Government Employees Health Association) administers plans in partnership with UnitedHealthcare. The standard filing window is 365 days (12 months) for most in-network providers, but the starting point varies by claim type.
Most participating, or in-network, healthcare providers have 365 days (12 months) to send a new claim to GEHA after care is delivered. For inpatient facility claims, the clock is measured from the date of discharge. For professional claims, it is measured from the date of service.
Network status variation: Out-of-network providers may receive less time under some GEHA plan types. Before relying on the full 365-day window, verify the specific plan type (Standard, High, HDHP, or Elevate) and the provider’s network status.
Secondary claims: GEHA typically allows 60 to 90 days from the primary insurer’s EOB date for secondary claims, or the broader one-year allowance, whichever is later. Some GEHA dental plans operate on a 90-day window with a December 31 deadline of the following calendar year.
A Scenario from the Field
Several years ago, I worked with a behavioral health practice that submitted claims to Carelon for services provided to members of a commercial health plan. The billing coordinator had been trained on a 90-day filing window and applied that deadline uniformly across all Carelon claims.
What she did not know was that one of the contracts the practice held included a state-specific Carelon provider manual that allowed 120 days for initial claims. The practice had been submitting claims at day 85 to 90 — within the window she believed applied — but some claims were arriving at day 91 to 95. Under the 90-day rule, those claims would have been timely. Under the actual contract, they had an extra 30 days that they never used.
The problem surfaced when a batch of claims was denied with CO-29. The practice assumed the denials were correct and wrote off approximately $14,000 over a six-month period. When a new billing manager reviewed the contract, she discovered that the applicable window was 120 days, not 90. Several of the denied claims had been submitted within the actual deadline and should not have been denied at all.
The practice appealed the denials with documentation of the contract terms. Some were overturned. Others were not, because the appeal window had already closed. The net loss was roughly $6,000 — revenue that would have been collected had the billing team verified the contract-specific deadline rather than relying on a default.
The lesson was straightforward: Carelon’s filing rules are contract-specific, not universal. The same principle applies to Ambetter’s state-by-state variation and Anthem’s Medicaid-versus-commercial distinction. Default deadlines are starting points, not answers.
How to Prove Timely Filing When a CO-29 Denial Arrives
A CO-29 denial (“The time limit for filing has expired”) is not always final. Payers will overturn it if the provider can demonstrate that the claim was submitted within the applicable window. The documentation required varies by payer, but the categories are consistent.
Clearinghouse acceptance reports: For electronic claims, the clearinghouse’s acceptance report (often a 277CA or proprietary acknowledgment) showing that the claim was accepted by the payer on a specific date is the primary proof. A rejected claim does not count as accepted; the clock keeps running until the claim is accepted.
Payer portal submission logs: For claims submitted directly through a payer portal (Availity, ProviderConnect, etc.), the portal’s submission confirmation or log serves as proof of timely filing.
Certified mail receipts: For paper claims, certified mail receipts with return receipt requested demonstrate the date the claim was mailed.
Primary payer EOP documentation: For secondary claims, the primary payer’s Explanation of Payment establishes the starting point for the secondary filing window.
Operational Controls to Prevent Timely Filing Denials
The most effective prevention is a payer-specific tracking system that does not collapse all deadlines into a single default.
Build a payer matrix. Document the initial, corrected, and secondary filing windows for every payer you bill. Update it when contracts are renewed or when payers publish policy changes.
Track by starting point, not just deadline. The clock starts differently for professional claims (date of service), facility inpatient claims (discharge date), and secondary claims (primary EOP date). A tracking system that uses a single starting point will miscalculate deadlines.
Monitor clearinghouse rejections daily. A rejected claim is not a filed claim. The timely filing clock continues running until the payer accepts the claim. Daily rejection review prevents claims from aging past the deadline while sitting in a clearinghouse queue.
Use proof-of-filing documentation for every submission. Retain clearinghouse acceptance reports and portal confirmation screens. When a CO-29 denial arrives, this documentation is the only path to overturning it.
Escalate contract-specific rules during onboarding. When a new payer contract is signed, add the filing deadlines to the payer matrix immediately. Do not assume they match the payer’s published default.
Frequently Asked Questions
1. What is the Anthem timely filing limit for commercial claims?
Anthem’s standard commercial and Medicare Advantage timely filing limit is 90 days from the date of service. Medicaid deadlines vary by state, often allowing 365 days. California Medi-Cal allows 180 days for participating providers and 210 days for non-participating providers.
2. What is the Aetna timely filing limit for in-network providers?
Aetna’s in-network commercial timely filing limit is 90 days from the date of service. Out-of-network (non-participating) providers have 12 months (365 days), reduced from 27 months effective January 1, 2022.
3. How long does Ambetter allow for claim submission?
Ambetter allows 180 days from the date of service for in-network providers in most states. Exceptions include Texas (95 days) and some other state-specific variations. Out-of-network providers in most states have 365 days.
4. What is the Carelon Behavioral Health timely filing limit?
Carelon’s default timely filing limit is 90 calendar days from the date of service or discharge. However, the actual deadline depends on the specific provider manual, state requirement, or contract terms. Some contracts allow up to 365 days.
5. What is the GEHA timely filing limit?
GEHA allows 365 days (12 months) from the date of service for most in-network providers. Inpatient facility claims are measured from discharge. Secondary claims typically have 60 to 90 days from the primary insurer’s EOB date.
6. Can a CO-29 timely filing denial be appealed?
Yes, if the provider can demonstrate that the claim was submitted within the applicable filing window. Clearinghouse acceptance reports, payer portal submission logs, and certified mail receipts serve as proof. The appeal window varies by payer.
7. What is the difference between a corrected claim and a secondary claim filing deadline?
A corrected claim deadline is measured from the original remittance or Explanation of Payment date. A secondary claim deadline is measured from the primary payer’s EOP date. Both differ from the initial claim deadline, which is typically measured from the date of service.
8. How often do payer timely filing limits change?
Payer filing limits change without announcement, often during annual contract renewals or policy updates. Anthem, Aetna, Ambetter, Carelon, and GEHA have all adjusted their windows in recent years. Billing teams should verify deadlines annually and whenever a contract is renegotiated.
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