What is Washington Timely Filing Law?
Washington Administrative Code 284-43A-200 requires health insurers to pay or deny clean claims within 20 business days of receipt. The clock starts on the day after the insurer receives the claim. If the claim is incomplete, the insurer must request missing information within 20 business days, and the clock restarts when complete information is received.
Interest on Late Claims
Under WAC 284-30-395, insurers must pay 1% interest per month on claims not paid within 20 business days. Interest accrues from the 21st business day through the date of actual payment. This penalty encourages timely payment and compensates providers for delayed cash flow.
Claim Acknowledgment Requirement
Washington requires insurers to acknowledge receipt of claims within 10 business days under WAC 284-30-360. This acknowledgment should confirm the claim was received and identify any missing information needed to process it.
Incomplete Claims
If a claim lacks required information, the insurer must request the missing details within 20 business days of receipt. A new 20-business-day payment period begins when the provider submits complete information. Providers and insurers should work together to resolve missing information quickly.
Enforcement
The Washington Office of the Insurance Commissioner (OIC) enforces timely filing requirements. Providers and patients may file complaints with the OIC for violations.
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Frequently Asked Questions
How do I calculate 20 business days in Washington?
Business days in Washington exclude weekends (Saturday and Sunday) and state and federal holidays. Count from the day after the claim is received by the insurer. For example, if a claim is received on a Monday, start counting Tuesday as business day 1.
What interest does Washington owe on a late claim?
Washington law (WAC 284-30-395) requires insurers to pay 1% interest per month on late claims. Interest accrues from the 21st business day after receipt through the date of payment. This amounts to 12% annually if the claim remains unpaid for a full year.
How to Collect Interest on a Late Washington Claim
- Calculate 20 business days from claim receipt date — Document the date the insurer received your claim. Count 20 business days (excluding weekends and holidays) to establish the deadline.
- Send a written demand letter to the insurer — Notify the insurer in writing that the claim is past the 20-business-day deadline and demand payment plus 1% monthly interest.
- File a complaint with the Washington Office of the Insurance Commissioner — If the insurer disputes your calculation or refuses payment, submit a formal complaint to the OIC including documentation of the claim and the timeline.
- Request accrued 1% per month interest in your formal demand — Calculate interest from the 21st business day through the payment date at 1% per month and include this amount in all correspondence and complaints.
Disclaimer: State laws change. This reference is current as of April 13, 2026. Consult Washington Administrative Code 284-43A-200 and 284-30-395, or a healthcare attorney for definitive guidance on your specific situation.