A bookkeeping engagement letter is the signed agreement that says what you will do for a client and what they must do in return. It must cover the services and their limits, the client's duties and statement deadlines, the fee and billing terms, how client data is handled, and how either side ends the work.
Which clauses belong in every bookkeeping engagement letter?
Every bookkeeping engagement letter needs seven clauses: the parties and start date, services, exclusions, client responsibilities, fees and billing, data handling, and termination. Anything else is optional. A letter missing one of these seven leaves a question that will eventually be answered in an argument rather than in writing.
The letter does two jobs at once. It sets expectations before the work starts, so the client knows what a month of service looks like. And it is the document both sides return to when something goes wrong, from a late payment to a disagreement over whether a task was included.
The checklist below gives each clause, what it settles, and an example line. The wording is illustrative and should be adapted to your practice. Because an engagement letter is a contract, have it reviewed by a lawyer who practices where you work before you use it.
| Clause | What it settles | Example line |
|---|---|---|
| Parties and start date | Who the agreement binds and when it begins | "This letter confirms the terms under which [Practice] will provide bookkeeping services to [Client LLC], beginning [date]." |
| Services | What you do each month | "Each month we will categorize transactions and reconcile the accounts listed in Schedule A." |
| Exclusions | What you do not do | "Our services do not include tax preparation, audits or payroll filings." |
| Client responsibilities | What the client provides, and when | "You will send all bank and card statements for the prior month by the 7th." |
| Fees and billing | Price, timing, late terms, changes | "The monthly fee is $[amount], invoiced on the 1st and due within 15 days." |
| Data handling | Files, access, software, retention | "Statements are stored in [system] and kept for [period] after the engagement ends." |
| Termination | How either side ends it, and the handover | "Either party may end this engagement with 30 days' written notice." |
| Signatures | Agreement by both sides | Name, title, date for each party |
Services and exclusions in the engagement letter
The services section of an engagement letter should name each task, how often it happens and which accounts it covers. The exclusions section should name the work clients most often assume is included but is not. Vague phrases such as "general bookkeeping" invite disagreement, while a list of accounts and a delivery date leaves nothing to interpret.
Write services as outputs the client can check:
- Categorize every transaction on the accounts in Schedule A.
- Reconcile each account to its statement each month.
- Deliver a profit and loss statement and balance sheet by the 15th of the following month.
- Send one consolidated list of questions each month.
Putting the account list in a schedule, rather than the body of the letter, means a new account can be added with a short signed amendment instead of a new letter.
Exclusions protect the fee. Common ones for a bookkeeping practice include tax returns, sales tax filings, payroll processing, bill payment, inventory counts, audit or review work, and any advice on legal structure. Naming them does not stop you offering them later. It simply makes them separately priced. The detail of writing this section well, including how to describe each deliverable, is covered in writing a bookkeeping scope of work clients understand.
Client duties and statement deadlines in the letter
The client duties section of an engagement letter states what the client must provide, in what form and by which day of the month. Bookkeeping depends on the client's documents, so this clause is what makes your delivery dates possible. Without it, every late close becomes your fault by default.
Typical duties for a monthly client:
- Statements by a set day. All bank, card and loan statements for the prior month by a named date, or access to download them.
- Answers within a set time. Replies to the monthly question list within a number of business days.
- Notice of changes. Telling you about new accounts, new loans, new employees and large purchases.
- Accurate information. The client is responsible for the truth of what they send.
- Final decisions. The client, not the bookkeeper, makes the business's financial decisions and approves the books.
Tie the duties to consequences. A line such as "if statements arrive after the 7th, delivery moves to 10 business days after they arrive" turns a deadline from a wish into a rule. If you take statements by upload or forwarding, say where they go. Clients who forward their bank's monthly email to one address send statements more reliably than clients who have to remember a portal.
Fee, billing and late payment terms in a bookkeeping engagement letter
The fee clause of a bookkeeping engagement letter states the monthly fee, when invoices go out, when payment is due, how payment is taken, what happens when it is late and how the fee can change. Each of these terms prevents a specific dispute, so each deserves its own sentence rather than a single line about "agreed fees".
Points to cover:
- The amount, and whether it is monthly, quarterly or annual.
- One-time fees, such as setup or catch up work, priced separately.
- Due date and method, for example card or bank debit on the 1st.
- Late payment, such as pausing work after a set number of days overdue.
- Out-of-scope work, billed at a stated hourly rate or quoted before it starts.
- Fee reviews, how often the fee is reviewed and how much notice a change gets.
The out-of-scope line matters more than it looks. Work grows slowly: one more account, one more report, one more call. A fee clause that names a review trigger, such as a new account or a set rise in transaction volume, turns that growth into a price change instead of free work. Scope creep in bookkeeping and how to price it shows how to spot the growth before it costs a quarter of your margin.
Data handling and statement storage clauses
The data handling clause says where client statements and records are kept, who can see them, which software processes them, and what happens to them when the engagement ends. Clients hand over bank statements that show every payment they make, so a short, specific clause here builds trust as much as it limits risk.
Cover four points:
- Where files live. The systems you store and process documents in, including any statement conversion or accounting software.
- Who has access. You, named staff or subcontractors, and the client's own advisors when the client asks.
- How long files are kept. A retention period, and what happens at the end of it.
- What happens at the end. Which records the client receives, in what format, and when your copies are deleted.
If you use outside software to convert or categorize statements, say so in the letter. Two posts cover the wording in detail: confidentiality terms for a bookkeeping engagement letter and engagement letter wording for client consent to software.
When the software is a converter such as AutoBankConvert, you can name it in the letter and state the retention period you have chosen for original statements after export, since that setting is yours.
How should termination and handover end a bookkeeping engagement?
A bookkeeping engagement ends by written notice from either side, with a stated notice period, a final invoice and an agreed handover of records. The termination clause should also allow immediate ending for serious cause, such as non-payment or a client asking you to record something false. Without this clause, leaving a bad client is slow and uncertain.
Write the termination clause in three parts:
- Notice. Either side may end the engagement with a set number of days' written notice. Thirty days suits most monthly work.
- Immediate termination. Either side may end it at once for listed reasons, such as unpaid invoices past a set date or a request to act dishonestly.
- Handover. On ending, you deliver the books through the last completed month, plus the original documents you hold, once outstanding invoices are paid.
Be precise about the last month. Say whether the final month of work is the month notice was given or the month the notice period ends, and whether partly finished months are billed.
Signed letters also matter beyond any one client. If you ever sell the practice, a buyer will look for a current signed letter for each client, since it shows which relationships are documented and transferable; selling a bookkeeping practice and preparing its records explains how that affects the price.
Engagement letter gaps that start fee disputes
The engagement letter gaps that start the most fee disputes are an unclear service list, no out-of-scope rate, no fee review clause, and an unsigned or outdated letter. Each one leaves a question about money unanswered. When the question comes up later, both sides answer it differently and both believe they are right.
Gaps to check for in your current letters:
- The letter describes the client as they were. A client who started with one account and now has four is working under a letter that prices one.
- No account schedule. Without a list, any new account is arguably included.
- No stated hourly rate for extras. The first extra invoice then becomes a negotiation.
- No catch up terms. A client three months behind on statements expects the next close at the normal fee.
- No signature from the right person. A signature from someone without authority to sign for the company, such as an office manager, may not bind it.
- No review date. Letters that never change drift away from the work.
A simple habit fixes most of these: review each client's letter once a year alongside the fee. If the work has changed, issue an amended schedule and have it signed. It takes minutes per client and settles the questions before they turn into disputes.