The client took the deliverable and stopped responding to invoices. What can a consultant actually do?
Consulting collection matters are almost always scope and acceptance fights dressed up as nonpayment matters. The client says "the deliverable wasn't what we asked for." The consultant says "you accepted the kickoff scope, the milestone signoffs, and the final report." Whether the collection succeeds turns on what the engagement letter or statement of work says about acceptance, what the milestone record shows, and whether the deliverable was used (a deliverable that was used is, almost by definition, accepted). This page walks the scope and acceptance analysis, then the standard Washington collection statutes: reciprocal fees under RCW 4.84.330, 12 percent default interest under RCW 19.52.010, and the dollar threshold that decides whether the offer-of-settlement fee path is available.
The scope and acceptance record
Three artifacts decide most consulting collection matters: the engagement letter or SOW (the source of truth on scope), the milestone or progress record (kickoff agenda, weekly status emails, mid-engagement reviews), and the final-deliverable acceptance record (the email or signoff confirming receipt of the deliverable). The cleanest collection file has all three. The messy file has a one-page proposal, no milestone documentation, and a deliverable that the client never explicitly signed off on but is now using or has referenced in subsequent work. A consultant unpaid-invoice demand letter has to address acceptance on the evidence available, not on assumption.
- Engagement letter or SOW: scope statement, deliverable list, milestone dates, payment schedule, acceptance procedure.
- Milestone record: meeting notes, status reports, intermediate deliverables, client comments and signoffs.
- Final acceptance: explicit signoff, or use of the deliverable (presentation referencing the report, code deployed to production, recommendations implemented).
The "deliverable was used" theory
Even without explicit acceptance, a deliverable that the client used effectively waives most scope objections. A client that received the strategy memo, took it to the board, and made decisions based on it cannot credibly claim post hoc that the memo was unsatisfactory. The demand letter should reference the use record specifically: the date of the board meeting, the screenshot of the deployed feature, the press release citing the recommendation. A use record converts a soft acceptance picture into a hard one.
What the consultant unpaid-invoice demand letter should do
- Identify the engagement letter or SOW and attach a copy.
- Walk the milestone record and final-acceptance evidence in plain language: "On [date] you confirmed the kickoff scope; on [date] I delivered milestone 1, you commented, I revised, you signed off; on [date] I delivered the final report; on [date] you referenced the report in [board memo / deployed code / press release]."
- State the balance owed with per-diem interest under RCW 19.52.010.
- Cite RCW 4.84.330 if the engagement letter has a fee clause, or RCW 4.84.250 if the matter is $10,000 or less and the offer-of-settlement procedure is available.
- Demand payment by a specific date, 15 business days from the letter.
- Identify the breach-of-contract theory and account-stated theory as alternative theories.
- Send certified mail to the client entity's registered agent and to the engagement signatory, plus email.
Hourly vs deliverable billing
Hourly consulting matters are messier than deliverable matters because the client can always claim the hours were excessive even if the scope was completed. The demand letter on an hourly file has to attach the time records in usable form (date, hours, narrative description) and reference the rate as stated in the engagement letter. If the engagement letter caps hours or sets a not-to-exceed amount and the bill exceeded it without written approval, the cap is the live issue and the letter has to address it head on.
Documents to upload before the letter goes out
- The engagement letter, SOW, or accepted proposal.
- Every milestone deliverable, status email, and client comment.
- The final deliverable in the form delivered, plus any explicit acceptance email.
- Use record: any client communication or external reference showing the deliverable was used.
- The invoices in the form sent.
- Time records (for hourly engagements) in their original form.
- The client's communications about the deliverable, payment, or scope.
When this becomes worth hiring an attorney
- Principal at issue above roughly $3,000.
- An engagement letter with a fee clause (or a matter $10,000 or less where RCW 4.84.250 is available).
- A client that is operating, with a brand and reputation that respond to attorney letters.
- A clean acceptance record (explicit signoff, use of the deliverable, or both).
What I review when you send the file
I read the engagement letter to find the fee clause and the acceptance procedure, then walk the milestone record to assess whether acceptance is established. I form a view on whether the file supports a $575 letter, whether the use record is strong enough to overcome a likely "deliverable was not what we asked for" defense, or whether the file needs tightening before a letter goes out.
Primary sources
- RCW 4.84.330: reciprocal attorney-fee statute.
- RCW 4.84.250: offer-of-settlement fee shift in actions of $10,000 or less.
- RCW 19.52.010: 12 percent default interest.
- RCW 4.16.040: six-year contract statute of limitations.
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.