How to Invoice as a Plumber in Washington

How to invoice as a plumber in Washington: WA sales tax 6.50% (applies to services), late fees capped at 1.5%/mo under Wash. Rev. Code §19.52.020. Step-by-step guide with a free template.

State sales tax
6.5%
Late fee cap
1.5%/mo
Net terms
14 days
Deposit
30%
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1. Washington-specific invoice requirements

  • Sales tax line: 6.50% state rate. Services billed to WA customers must include sales tax. State 6.5%; many services taxable. Combined commonly 8.5-10.5%.
  • Late-fee cap: Washington statute Wash. Rev. Code §19.52.020 caps interest on unpaid invoices at 1.5% per month. Spell out the rate in writing on every invoice and in your contract — courts won't enforce undisclosed fees.
  • Right-to-cancel notice: Customers in Washington get 72-hour cancellation rights on certain home-services contracts. Disclose this in your terms.

2. Plumber line items + standard terms

Every plumber invoice in Washington should itemize work clearly. Standard plumbers use Net 14 terms with a 30% deposit required upfront.

  • Service call fee — billed by flat (~$95 default).
  • Labor — billed by hour (~$110 default).
  • Materials — billed by itemized.

3. Plumber licensing in Washington

State-licensed in most states. Master plumber license typically required for self-employment.

4. Send and follow up

Send the invoice the same day work completes. Use software that records open events and offers a one-click online payment so you don't need to chase a check by mail. Washington customers expect digital payment options today — accepting card and ACH typically reduces days-to-paid by 30–50%.

Average invoice
$485
State
WA
Net terms
14 days
Deposit
30%

Washington metro guides

Metro-specific guides include the combined sales-tax rate and local pricing benchmarks.

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