## Washington interest rules

This source-backed guide covers US-WA interest authority (RCW 4.56.110; RCW 19.52.010; RCW 19.52.020; RCW 59.18.270). It certifies only the quoted source-backed rules below; related interest categories remain outside this page unless they are expressly listed in the receipt.

## RCW 4.56.110; RCW 19.52.010; RCW 19.52.020; RCW 59.18.270

US-WA interest controlling authority under RCW 4.56.110; RCW 19.52.010; RCW 19.52.020; RCW 59.18.270.

> **4.56.110.** Interest on judgments shall accrue as follows: (1) Judgments founded on written contracts, providing for the payment of interest until paid at a specified rate, shall bear interest at the rate specified in the contracts: PROVIDED, That said interest rate is set forth in the judgment. (2) All judgments for unpaid child support that have accrued under a superior court order or an order entered under the administrative procedure act shall bear interest at the rate of twelve percent.

## Use the calculator

DocketMath's interest calculator can model interest scenarios once you identify the controlling jurisdiction, amount, rate type, and accrual date. Use the source panel for the verified source-backed rule.

[Open the Interest calculator](/tools/interest)

## Sources

- [4.56.110 — RCW 4.56.110; RCW 19.52.010; RCW 19.52.020; RCW 59.18.270](https://app.leg.wa.gov/rcw/default.aspx?cite=4.56.110)

All sources are official primary law published by `app.leg.wa.gov`.

**Corroboration method:** government_primary_source_direct_fetch.


DocketMath’s Judgment Interest Calculator for Washington (US-WA) helps you compute interest accruing on a judgment using a date range you select and a s...

Judgment Interest Calculator Guide for Washington

Receipt-backed Washington interest surface. The receipt certifies judgment-interest categories, default and maximum rates, May 2026 State Register values, and security-deposit interest allocation only.

Interest on judgments shall accrue as follows: (1) Judgments founded on written contracts, providing for the payment of interest until paid at a specified rate, shall bear interest at the rate specified in the contracts: PROVIDED, That said interest rate is set forth in the judgment. (2) All judgments for unpaid child support that have accrued under a superior court order or an order entered under the administrative procedure act shall bear interest at the rate of twelve percent.

(3)(a) Judgments founded on the tortious conduct of a "public agency" as defined in RCW 42.30.020 shall bear interest from the date of entry at two percentage points above the equivalent coupon issue yield, as published by the board of governors of the federal reserve system, of the average bill rate for twenty-six week treasury bills as determined at the first bill market auction conducted during the calendar month immediately preceding the date of entry.

The maximum allowable interest rate applicable for the month of May 2026 pursuant to RCW 19.52.020 is twelve point zero percent (12.00%) per annum. The auction yield of the April 6, 2026 auction of the six-month Treasury Bill was 3.733%% The interest rate required by RCW 4.56.110 (3)(a) and 4.56.115 for the month of May 2026 is 5.733%%. The interest rate required by RCW 4.56.110 (3)(b) and 4.56.111 for the month of May 2026 is 8.750%.

Except as provided in subsection (2) of this section, every loan or forbearance of money, goods, or thing in action shall bear interest at the rate of twelve percent per annum where no different rate is agreed to in writing between the parties

any rate of interest shall be legal so long as the rate of interest does not exceed the higher of: (a) Twelve percent per annum; or (b) four percentage points above the equivalent coupon issue yield (as published by the Board of Governors of the Federal Reserve System) of the average bill rate for twenty-six week treasury bills

Unless otherwise agreed in writing, the landlord shall be entitled to receipt of interest paid on such trust account deposits.

For Washington interest pages, use RCW 4.56.110 for judgment-interest categories, RCW 19.52.010 for the no-written-rate default loan/forbearance rate, RCW 19.52.020 for the maximum lawful rate, the Washington State Register current-rate table for current monthly values, and RCW 59.18.270 for tenant security-deposit interest allocation.

interest in US-WA is governed by RCW 4.56.110; RCW 19.52.010; RCW 19.52.020; RCW 59.18.270.