How to Invoice as a Mobile App Developer in Washington

How to invoice as a mobile app developer 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
30 days
Deposit
33%
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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. Mobile App Developer line items + standard terms

Every mobile app developer invoice in Washington should itemize work clearly. Standard mobile app developers use Net 30 terms with a 33% deposit required upfront.

  • Sprint / milestone — billed by flat.
  • Hourly — billed by hour (~$165 default).
  • App Store submission — billed by flat.
  • Maintenance retainer — billed by flat.

3. Mobile App Developer licensing in Washington

No license required. App Store and Play Store policies must be honored.

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
$8,500
State
WA
Net terms
30 days
Deposit
33%

Washington metro guides

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

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