Washington educational resource

An invoice has been outstanding for months. What does Washington law actually give a small business?

Most Washington unpaid-invoice matters do not look like the textbook collections case. The contract is an email chain or a one-page services agreement, the work was delivered before payment, and the debtor has gone silent or is slow-walking. The questions that actually decide leverage are narrow: does your contract have an attorney-fee clause (which is the difference between recovering fees and eating them), is there a written interest rate (which controls whether the 12 percent statutory default applies), and do you have the signed acceptance or purchase order that proves the amount is liquidated. This hub walks the four or five statutes that decide those questions and links to the matter-specific demand letter pages. The general theme: Washington gives you usable tools, but only when the contract record supports them.

Last legally reviewed: 2026-05-19. Operative text for RCW 4.84.330, RCW 19.52.010, RCW 19.52.020, RCW 19.16.250, Chapter 4.84 RCW, and RCW 62A.3-520 retrieved from app.leg.wa.gov. Verify the live chapter text before relying on a specific subsection in a live matter; this page is informational only.

The four statutes that decide most Washington collections matters

RCW 4.84.330 is the reciprocal attorney-fee statute. It takes a one-way attorney-fee clause in a contract or lease (the standard form: "creditor recovers fees if creditor sues to collect") and makes it run both ways, so the prevailing party recovers, regardless of which side the clause names. The text says the prevailing party in any action on a contract or lease that specifically provides for attorney's fees and costs to enforce shall be entitled to reasonable attorney's fees in addition to costs and necessary disbursements. Two practical effects: (1) if your services agreement has a fee clause, you can recover fees on collection even if the clause was originally drafted to protect the customer; (2) if the debtor argues anything other than that the invoice was paid in full, fee exposure starts running on both sides the moment you file. Source: RCW 4.84.330.

RCW 19.52.010 sets the statutory default interest rate at 12 percent per year when no other rate is agreed in writing. The pre-judgment interest piece matters because most service contracts do not specify a rate, and most invoices that go unpaid sit at zero interest under the contract itself. The 12 percent default fills that gap. RCW 19.52.020 sets the highest contractual rate the parties may legally agree to (calculated under a formula tied to federal reserve rates with a 12 percent floor). The combined effect: the parties can agree to a higher rate up to the statutory ceiling, and absent a written rate, the default is 12 percent. Sources: RCW 19.52.010, RCW 19.52.020.

RCW 19.16.250 regulates collection agencies. The provision matters for two reasons. First, it limits what a licensed collection agency may add to the underlying debt: interest at the contract rate or the statutory default, allowable late fees if the original contract supports them, and court costs and fees recoverable by statute or contract. Charges beyond those are unlawful. Second, the same regime constrains assigned debt, so a small business that sells its receivables to a collection agency does not escape the limits by selling. The takeaway for an original creditor: do not pad the invoice with "collection costs," "administrative fees," or "interest" not provided for in the contract. If you do, you weaken your case and may give the debtor a counterclaim. Source: RCW 19.16.250.

Chapter 4.84 RCW sets the attorney-fee framework in smaller actions. RCW 4.84.250 through .300 give the prevailing party in a damages action of $10,000 or less attorney's fees against the losing side, but only if the prevailing party served a written offer of settlement in compliance with the statute. The rule is technical: the offer must be made at least ten days before trial, the recovery has to be as favorable or more favorable than the offer, and the dollar amount in controversy has to be $10,000 or less exclusive of costs. Used correctly, it converts a marginal small-dollar collection action into a fee-recovery vehicle. Used incorrectly, it produces nothing. Source: Chapter 4.84 RCW.

RCW 62A.3-520 is the dishonored-check statute. When a check is returned for nonsufficient funds or stopped without justification, the maker is liable for the face amount plus a handling fee not exceeding $40, plus interest. If the holder serves a statutory notice and the maker still does not pay, the holder may recover up to three times the face amount of the check (capped at $300) as a statutory remedy, plus reasonable attorney's fees and costs. This is the rare Washington statute that supplies its own fee shift even where the underlying agreement does not. Source: RCW 62A.3-520.

The matter-specific demand letter pages

Each link below covers a single fact pattern. The matter type controls which evidence matters, which clauses in the contract are load-bearing, and what the realistic settlement number looks like.

• Washington unpaid invoice demand letter: the general framework for a written services or sales invoice that has aged past due. Walks the contract review, the fee-clause check, the interest calculation, and the certified-mail delivery.
• Washington business debt demand letter: B2B collection where both sides are businesses. Covers personal guaranty issues, signed-acceptance proof, and when an account-stated theory adds leverage.
• Washington contractor unpaid invoice demand letter: contractor-to-customer billing dispute (the demand letter from the contractor's side; the customer-side defect-notice analysis lives on the contractor-disputes page).
• Washington consultant unpaid invoice demand letter: deliverable-based professional-services billing where scope and acceptance are usually the live issues.
• Washington SaaS unpaid invoice demand letter: subscription billing, mid-term cancellation, suspension-of-service questions, and online-acceptance evidence.
• Washington vendor payment demand letter: goods delivered, purchase order issued, payment not made. Often crosses into Article 2 UCC territory.
• Washington promissory note demand letter: written-instrument collection with maturity date, default acceleration, and (sometimes) personal guaranty.
• Washington dishonored check demand letter: the statutory notice under RCW 62A.3-520 that converts a bounced check into a fee-shifting and treble-damages case.
• Washington accounts receivable collection letter: portfolio-style collection on a stack of aged invoices. Touches assignment, collection-agency licensing, and limits on what may be charged.

Sergei's practical note

A clean unpaid-invoice file is straightforward. There is a signed agreement or a purchase order, the work was delivered or the goods were shipped, the invoice was sent, and the debtor went silent. On that record, a $575 attorney demand letter on letterhead with the statutory interest calculation, a copy of the contract attached, and a 15-business-day response window often settles the matter. The cases that do not settle on a letter are the ones where the debtor has a real (or plausible-sounding) dispute the original creditor papered over: a scope question, an acceptance question, a quality question. On those files, a demand letter that does not engage the dispute looks weak and invites a counter-letter that costs you leverage. The right first move on a disputed file is usually a $125 written email evaluation to figure out what the actual record supports before the letter goes out.

The unpaid-invoice demand calculator

For a fast triage, the Washington Unpaid Invoice Demand Calculator takes the principal, the invoice date, the partial payments, and the contract questions, then estimates statutory interest, fee-recovery posture, dispute risk, and a documentation-strength score. The calculator is not a substitute for the evaluation; it is a starting point.

When this becomes worth hiring an attorney

• Principal at issue above roughly $2,000 (below that, small claims is faster and the fee math rarely works).
• A written contract with an attorney-fee clause, or a personal guaranty, or a purchase order with signed acceptance.
• Debtor is a real business with assets and a brand it values; not a judgment-proof shell.
• The dispute is over nonpayment, not over scope, quality, or breach. If the dispute is on the merits, the letter has to address the merits.
• An arbitration clause in the underlying agreement. The forum question changes the cost and timeline analysis and is worth attorney review before the demand letter is sent.

Documents to upload before the letter goes out

• The signed services agreement, sales agreement, master agreement, or order form (and any amendments).
• The purchase order, signed acceptance, or work-authorization email or text from the debtor.
• The unpaid invoice(s) in the form sent, plus any subsequent statements of account.
• The delivery proof: timesheets, shipping records, milestone signoffs, completion certificates.
• The aging report or a one-line ledger showing principal and any partial payments with dates.
• Any written communications from the debtor: acknowledgments, payment promises, denial, complaints about scope or quality.
• Personal guaranty or guarantor signature page if one exists.
• If a check bounced: the front and back of the dishonored check, the bank notice, and the date you learned of dishonor.
• If a collection agency or assignee has been involved at any point: every assignment record and every communication.

Primary sources

Primary statutory sources for this hub, retrieved on 2026-05-19 from app.leg.wa.gov:

• RCW 4.84.330: reciprocal attorney-fee statute (one-way fee clauses run both ways).
• Chapter 4.84 RCW: attorney fees in actions of $10,000 or less; offer-of-settlement procedure (RCW 4.84.250 through .300).
• RCW 19.52.010: 12 percent statutory default interest absent a written rate.
• RCW 19.52.020: ceiling on contractual interest rate.
• RCW 19.16.250: collection-agency restrictions on amounts collected beyond allowable interest, late fees, and statutory costs.
• RCW 62A.3-520: dishonored-check notice; up to three times face amount, capped at $300, plus reasonable attorney fees and costs.

This page is an educational resource. Sergei Tokmakov is a California attorney (CA Bar #279869) currently seeking admission to the Washington State Bar. Nothing on this page creates an attorney-client relationship, and nothing on this page is Washington legal advice for a specific matter. A Washington-admitted attorney should verify both the operative statute text and any case citations before relying on them in court or correspondence on a live dispute.