Glossary
Engagement Letter
An engagement letter is a written agreement, signed before work begins, that states which services an accounting or bookkeeping firm will provide, what the client is responsible for, how and when the firm bills, and how either side can end the arrangement. It is the document both sides point back to when there is a question about what was agreed.
What the letter is actually for
An engagement letter is not paperwork that happens after a firm and a client agree to work together. It is the document that defines the agreement — scope, fee, responsibilities, and an end point — in writing, before any bank access is requested or any billing starts. Firms that treat it as a formality signed after the fact lose the thing it is supposed to give them: a specific written answer to “what did we actually agree to” when a client asks for something that was never priced in.
The clauses that repeat across firms
Engagement letters differ in tone and length, but the structure converges on a short list almost everywhere:
| Clause | What it settles |
|---|---|
| Scope of services | Exactly which work is included — and, by omission, what is not |
| Fees and billing | Amount, frequency, and what triggers a change in price |
| Client responsibilities | What the client must provide and by when |
| Firm responsibilities | What the firm commits to deliver and on what cadence |
| Term and termination | How long the engagement runs and how either side exits |
| Confidentiality and data handling | How financial data is stored and who can see it |
| Signature block | Dated signatures from both sides — the point the engagement starts |
The scope clause carries the most weight in practice. A bookkeeping engagement letter names recording work — transaction coding, reconciliation, monthly reports — and usually states plainly that the firm is not auditing the records or giving tax advice. An accounting engagement letter that includes compilations, tax returns, or advisory work names each service separately, because bundling them into one vague line is what lets scope creep in later.
Why it comes before onboarding, not during it
The signed letter is normally the gate on a client onboarding checklist, not a step somewhere in the middle of it. Firms that request bank access or start work before the letter is signed lose the leverage the letter is meant to provide: once the work has started, a client has less reason to sign something that was supposed to define terms in advance. Requiring the signature first, and routing it through e-signatures rather than a printed page that sits in an inbox, keeps that order intact without slowing onboarding down.
Fees, billing, and what happens when scope changes
The fee clause should say more than a number. It should say what happens when the engagement changes shape — a client who started as bookkeeping-only and now wants payroll, or a transaction volume that has doubled since the letter was signed. Firms that leave this vague end up doing extra work on the original fee, one small request at a time. Naming the fee cadence in the letter is also what lets automated billing invoice on schedule without someone manually deciding, month to month, whether it is time to send an invoice.
Where the signed letter lives afterward
A signed engagement letter is referenced constantly after the fact — during a dispute about scope, at renewal, when a client asks why a fee changed. It belongs in the same place as the rest of the client’s file rather than in a personal inbox, both for the firm’s own reference and because document management that keeps signed agreements attached to the client record is what makes the letter useful a year later instead of a file someone has to go searching for.
When a new letter is actually needed
Reissuing every year is a common habit, but what actually forces a new letter is a change: different services, a different fee, a new deadline structure, or new responsibilities on either side. This matters most at the boundary between engagement types — a client who started with a bookkeeping cleanup and is moving into outsourced bookkeeping needs a new letter for the recurring service, because the cleanup’s terms were never written to cover ongoing work.
How Uku handles engagement letter
Last updated September 19, 2026 Reviewed by Rain Allikvee
