What is timely filing in medical billing?

Timely filing is the contractual or statutory deadline set by an insurance payer within which a medical provider must submit a clean healthcare claim following the date of service (DOS). Missing this deadline results in an uncollectible CO-29 denial that cannot be billed to the patient.

What is the timely filing limit for Medicare Part B?

Under federal statute (Affordable Care Act Section 6404), the timely filing limit for Medicare Part A and Part B claims is 1 calendar year (365 days) from the date of service.

What is the timely filing limit for UnitedHealthcare (UHC)?

UnitedHealthcare enforces a strict 90 calendar day timely filing limit from the date of service for participating in-network providers, while appeals must be filed within 180 days of the initial denial date.

What is the timely filing limit for Aetna?

Aetna's standard participating provider contract enforces 90 calendar days from the date of service for initial claims, with 180 calendar days for Level 1 provider reconsiderations.

What counts as acceptable electronic proof of timely filing?

Payers strictly demand objective electronic clearinghouse documentation: specifically the EDI 277CA Acceptance Acknowledgment Report showing gateway acceptance prior to the deadline, or an EDI 837 batch transmission confirmation. Internal PM/EHR screenshots are universally rejected.

How is timely filing calculated for secondary insurance claims?

For secondary claims, the timely filing clock resets on the date of the primary payer's Explanation of Benefits (EOB) or 835 Remittance Advice (typically 90 to 180 days from the primary adjudication date), rather than the original date of service.

2026 Edition Commercial, Medicare, Medicaid & Military Payers

Payer Timely Filing Limits & Deadlines Calculator

Calculate exact submission deadlines, countdown days remaining, appeal windows, and accepted clearinghouse proof for 25+ major health plans to prevent unrecoverable CO-29 timely filing write-offs.

Claim Deadline Calculator

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Select Insurance Payer

Submission Stage / Claim Type

Date of Service (DOS)

Select the date care was provided, or primary EOB date for secondary/appeal.

Why Timely Filing Matters

Once a timely filing limit expires, payers legally refuse payment (denial code CO-29). Under in-network contracts, you are legally prohibited from balance-billing the patient.

Calculation Result

Calculating...

Filing Deadline Date

90 calendar days from Date of Service

Filing Window

90 Days

Days Remaining

-- Days

Accepted Electronic Proof of Timely Filing

Clearinghouse 277CA acceptance acknowledgment report...

Timely Filing Appeal Letter Template

Subject: Appeal of Timely Filing Denial (CO-29) with Clearinghouse Gateway Proof
Claim ID: [Claim Number] | Patient: [Patient Name] | DOS: [Date of Service]

We are appealing the timely filing denial for the above referenced claim. The contractual limit for [Payer Name] is [Days] days. Attached as Exhibit A is our electronic clearinghouse EDI 277CA Acceptance Acknowledgment proving initial submission on [Submission Date] well prior to the deadline.

2026 Payer Timely Filing Reference Matrix

Quick reference directory of initial submission deadlines, secondary claim limits, appeal windows, and proof standards across 25+ major health plans.

Payer / Plan	Initial Limit	Secondary Claim	Appeal Window	Action
UnitedHealthcare (UHC) Commercial / Medicare Advantage	90 Days	90 Days from EOB	180 Days	Guide →
Aetna Commercial / Medicare Advantage	90 Days	90 Days from EOB	180 Days	Guide →
Cigna Healthcare Commercial / Medicare Advantage	90 Days	90 Days from EOB	180 Days	Guide →
Blue Cross Blue Shield (BCBS National / Federal) Commercial / Federal Employee Plan (FEP)	365 Days	180 Days from EOB	180 Days	Guide →
Medicare (Part A & Part B Traditional / CMS) Federal Government / CMS	365 Days	365 Days from EOB	120 Days	Guide →
Medicare Advantage (CMS MA Part C Plans) Medicare Advantage / Part C	365 Days	180 Days from EOB	60 Days	Guide →
Humana Commercial / Medicare Advantage	90 Days	90 Days from EOB	180 Days	Guide →
Anthem / Elevance Health Commercial / Medicaid / Medicare	90 Days	90 Days from EOB	180 Days	Guide →
Tricare (Military Health System / DHA) Military & Defense Health Agency	365 Days	365 Days from EOB	90 Days	Guide →
Veterans Affairs (VA Community Care Network / CCN) Veterans Health Administration	180 Days	180 Days from EOB	365 Days	Guide →
Centene / Ambetter / Health Net Medicaid Managed Care & ACA Exchange	95 Days	90 Days from EOB	90 Days	Guide →
Molina Healthcare Medicaid & Marketplace	90 Days	90 Days from EOB	90 Days	Guide →
Kaiser Permanente Integrated HMO / Commercial	180 Days	90 Days from EOB	180 Days	Guide →
Oscar Health ACA Marketplace / Commercial	90 Days	90 Days from EOB	180 Days	Guide →

Get the 2026 Payer Timely Filing Reference Matrix (PDF)

Download a printable 1-page desk reference of timely filing limits, secondary submission rules, appeal deadlines, and required clearinghouse proof for 40+ national health plans.

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Frequently Asked Questions: Timely Filing in Medical Billing

Answers to common questions regarding filing deadlines, proof standards, and CO-29 appeals.

Almost all major commercial insurers (UnitedHealthcare, Aetna, Cigna, Humana, BCBS) and government programs (Medicare, Medicaid) calculate timely filing in calendar days, not business days. If day 90 falls on a Saturday, Sunday, or federal holiday, most payers allow transmission on the following business day, but submitting several days in advance is strongly advised.

Internal software screenshots only prove when a biller entered or queued a claim inside their local office database; they do not prove the claim was ever electronically transmitted across EDI networks or accepted by the payer's gateway. Payers strictly demand independent third-party proof, such as the clearinghouse EDI 277CA Claims Acknowledgment.

ClaimCure automatically tracks payer-specific timely filing countdown clocks across all open encounters. Claims approaching 30, 60, and 75 days post-service are dynamically prioritized in scrubbing queues, and clearinghouse 277CA acceptance confirmations are automatically logged into the permanent audit ledger.

Payer Timely Filing Limits & Deadlines Calculator

Claim Deadline Calculator

2026 Payer Timely Filing Reference Matrix

Get the 2026 Payer Timely Filing Reference Matrix (PDF)

Frequently Asked Questions: Timely Filing in Medical Billing

What is the difference between calendar days and business days for timely filing?

Why are practice management software screenshots rejected as proof of timely filing?

How does ClaimCure prevent timely filing denials before they happen?