Bookkeeping engagement letter: what to include

A bookkeeping engagement letter earns its keep the first time a client disputes an invoice. The client signed up for “monthly bookkeeping” at a flat fee, the first bank feed turned out to be nine months behind, and now the firm wants to bill for the backlog while the client thinks it was included. Whoever has the clearer letter wins that conversation, and most letters copied from a template say nothing about it.

This post goes through what the letter has to settle, section by section, with the clauses templates usually leave out: cleanup versus monthly work, the client’s cutoff dates, who owns the QuickBooks file when the engagement ends, and what to say when some of the work is done by a subcontractor. It is written for firm owners, with a section for business owners reading one before they sign. It is not legal advice, and it is not a template. Ledgerbrook does bookkeeping, not contracts; have an attorney in your state review the letter you actually send.

What a bookkeeping engagement letter includes

These are the 8 sections, in the order most letters put them, and the argument each one prevents:

Section	What it settles	The dispute it prevents
1. Scope	Which accounts, which months, and which kind of work: cleanup, catch-up or monthly	“I thought the backlog was included”
2. Client obligations	What the client provides, in what form, and by which day	Late statements blamed on the bookkeeper
3. Fees and extra charges	The fee, what it covers, and what changes it	An invoice the client did not expect
4. Reporting schedule	Which reports, on what basis, by which day of the month	“Where are my financials?”
5. File ownership and access	Who holds the QuickBooks subscription, who is admin, what happens at the end	A file held hostage, or lost
6. Confidentiality and outside help	How client data is protected and whether anyone outside the firm works on it	A client surprised by a subcontractor
7. Liability limits	What the bookkeeper is not responsible for, and any cap	Blame for errors in the client’s own records
8. Termination	Notice, the final invoice, and what is delivered when it ends	A half-finished month with no owner

Identification of the parties, the effective date and the signature block are in every letter and need no explanation. The sections below are the ones that take thought.

Is a bookkeeping engagement letter required?

For bookkeeping alone, usually not by any professional standard. It depends on who is doing the work:

• A bookkeeper who is not a CPA. No accounting standard applies. The letter is an ordinary services contract, and its value is the record of what both sides agreed.
• A CPA firm doing bookkeeping only. The AICPA’s standard for preparing financial statements, AR-C section 70 of SSARS No. 21, applies only when the accountant is engaged to prepare financial statements. The Journal of Accountancy’s reading is that an accountant who posts entries and reconciles accounts is “engaged to provide accounting or bookkeeping services, and Section 70 of SSARS No. 21 does not apply,” and it advises saying in the engagement letter that the engagement does not include preparing financial statements (Bookkeeping service or preparation service?, January 2016).
• A CPA firm that also audits, reviews or compiles for the same client. Bookkeeping is then a nonattest service for an attest client, and the AICPA independence rules require the client to take on all management responsibilities and designate someone with suitable skill, knowledge or experience to oversee the work (ET §1.295.040). Before the work starts, the firm must document in writing the objectives, the services, the client’s acceptance of its responsibilities, the firm’s responsibilities and any limits (Maintaining independence with nonattest services). An engagement letter is the usual way to do it.

Whatever the standards say, a firm that starts work without a signed letter has only emails to point to when the scope is questioned.

1. Scope: name the accounts and the months

“Monthly bookkeeping for ABC LLC” is not a scope. A scope a third party could check lists:

• Every account in the engagement, by bank and last four digits: two checking accounts, one savings, two credit cards, a loan. An account the client opens later is outside the scope until the letter, or an addendum, adds it.
• The period. The first month the firm is responsible for, and whether anything before it is in scope.
• The kind of work. Cleanup corrects months that exist in QuickBooks but are wrong. Catch-up enters months that were never recorded. Monthly bookkeeping keeps a file current once it is right. They are priced differently, so the letter should say which one is being bought, and that a backlog found after signing is quoted separately. The difference is explained in QuickBooks cleanup vs catch-up.
• The tasks. Categorizing bank and card transactions, reconciling each account every month, entering bills, recording payroll from the provider’s reports, month-end adjusting entries. Name the ones you do.

What the letter should exclude

Exclusions are where most disputes start, so list them by name:

• Preparing or filing tax returns, including sales tax returns and payroll tax filings, unless separately engaged.
• Filing 1099s, unless separately engaged. If you do file them, say who collects the W-9s.
• Representing the client before the IRS or a state. Circular 230 limits practice before the IRS to attorneys, CPAs, enrolled agents and a few other credentialed groups (§10.3), with narrow exceptions (Treasury Department Circular No. 230). The best known is the Annual Filing Season Program: participants can represent clients only on returns they prepared and signed, and only before revenue agents, customer service representatives and the Taxpayer Advocate Service (IRS).
• An audit, review or compilation, and for a CPA firm, preparing financial statements under SSARS (see above).
• Tax, legal or investment advice.
• Signing checks, approving payments or moving the client’s money. If the firm does pay bills, the letter should say who approves each payment and that the firm never has signing authority.
• Detecting fraud or theft. Bookkeeping is not designed to find either, and the letter should say so.

2. Client obligations and cutoff dates

The client’s side of the work decides the firm’s deadlines, so the letter should put dates on it:

• What the client provides. Statement access (bank feeds, or statements by a set day each month), receipts for card charges over a stated amount, payroll reports if a third party runs payroll, and answers to questions.
• How fast. “Answers flagged transactions within five business days” turns a stalled month into the client’s delay, in writing.
• Accuracy. The client is responsible for the information it gives and for its own business decisions; the firm relies on what it is told.
• Tax-season cutoffs. If the books feed a return, put the date the books will be closed in the letter, and the date the client’s information must arrive for that to happen. For calendar-year 2026, S corporation and partnership returns are due Monday, March 15, 2027, and individual returns Thursday, April 15, 2027. A letter that says “year-end documents by February 15 for a March 15 return; anything later means the return goes on extension” makes the extension the client’s choice, not the firm’s failure. The full calendar is on business tax deadlines.

3. Fees and what triggers extra charges

State the fee, what it covers and what moves it:

• The fee and its basis. A flat monthly fee, a fee per month of backlog for cleanup or catch-up, or hourly. If the fee is set by a band, define the band’s unit. Is a “transaction” every bank and card line, or every entry in the ledger? The choice between models, and the clause that keeps a band honest, is in bookkeeping pricing models.
• What changes it. New accounts, transaction volume above the band, a new entity, payroll or inventory added, a backlog discovered after signing, work the client asks for that is on the excluded list.
• When the fee is reviewed. “Reviewed each January against the trailing three months” makes the next price change a clause, not a negotiation.
• Payment terms. Due date, payment method, and what happens when an invoice is unpaid: usually that work pauses after a stated number of days. Interest and late fees are limited by state law, so take that one to your attorney.

4. Reporting schedule

Say what the client receives, and when:

• Which reports. Profit and loss, balance sheet, the reconciliation report for each account, and anything else promised (A/R aging, budget comparison).
• The basis. Cash or accrual, matched to how the return is filed, or the reports will not agree with it.
• The date. “By the 10th business day after month end, provided statements and answers arrived by the 5th.” Tie the firm’s date to the client’s.
• What the reports are not. For internal management use; not audited, reviewed or compiled, and no assurance is given on them. For a CPA firm on a bookkeeping-only engagement, this is also where the letter says no financial statements are being prepared under SSARS.

5. File ownership and access

Most templates say the books belong to the client and stop there. In QuickBooks Online the questions are more specific:

• Whose subscription is it? A client-billed file belongs to the client’s Intuit account. An accountant-billed file, on the firm’s wholesale plan, is paid by the firm. The letter should say which, who pays Intuit, and what happens to the subscription when the engagement ends.
• Who is primary admin? Make it the client. Intuit’s own steps for moving billing from an accountant to the client require primary admin access: the client selects Transfer billing to myself, chooses a plan, enters payment details and accepts the emailed transfer, and the subscription is then priced at Intuit’s current rates (Transfer billing from accountant to you, updated August 5, 2026). A file where the firm is primary admin has to be handed back before the client can do any of that.
• Who has user access? The firm, and anyone working for it, as accountant users. The letter should say access is removed on termination, and by when.
• Records at the end. The client’s records go back to the client. A CPA firm is also bound by the AICPA’s records requests interpretation (ET §1.400.200), under which client-provided records in the firm’s custody are returned on request (Journal of Accountancy, August 2020), and a state board can be stricter. The firm’s own working papers are a separate category; say which you keep.

6. Confidentiality and outside help

The confidentiality clause should say how client data is handled and stored, and whether anyone outside the firm will see it: software vendors, a payroll provider, a subcontracted bookkeeper.

The handling part is not optional either. The IRS treats tax and accounting professionals as financial institutions under the Gramm-Leach-Bliley Act, and says “federal law requires tax and accounting professionals to create and maintain a Written Information Security Plan” (IR-2026-92, August 18, 2026). The letter does not need to reproduce that plan, but what it promises about storage and access should match it.

For a CPA firm, that last part is a rule, not a courtesy. The AICPA’s “Use of a Third-Party Service Provider” interpretation (ET §1.150.040) requires the firm to tell the client, preferably in writing, that a third party may be used, before confidential information goes to it, and the Journal of Accountancy notes the engagement letter can carry that disclosure (Working with third-party experts, November 2022). The confidentiality interpretation (ET §1.700.040) then requires either a contract with the provider to keep the information confidential or the client’s specific consent. The next section covers the wording.

7. Liability limits

The usual clauses:

• The firm is not responsible for errors that come from incomplete or inaccurate information the client provides.
• The engagement is not designed to detect fraud, theft or illegal acts.
• Any liability is capped, often at the fees paid for the services in question over a set period.
• Any claim must be brought within a stated time.

How far a cap is enforceable varies by state and by the kind of claim, which is why this is the clause most worth an attorney’s hour. If the firm carries professional liability insurance, ask the insurer: carriers publish their own recommended engagement letter language and may require certain terms.

8. Termination: how either side ends it

A letter that says either side may end it “on 30 days’ written notice” is half a clause. The other half says what happens next:

• The last month the firm will close, and that it will be reconciled and delivered.
• The final invoice, including any work in progress.
• The date the firm’s user access, and any subcontractor’s, is removed.
• The subscription and admin hand-back from section 5, if the firm held either.
• What the firm keeps, and for how long.

What the letter should say when the work is subcontracted

A firm that sends production work to a white-label or subcontract provider needs the engagement letter and the subcontract to agree with each other. The client signs one; the provider signs the other.

In the client’s engagement letter:

• The disclosure. A sentence saying the firm may use third-party service providers, bound by confidentiality, to perform some of the work, and that the firm remains responsible for it. That covers the AICPA notice for a CPA firm, and it is honest for any firm. The rule asks for notice that a third party may be used, not the provider’s name.
• Where the work happens. Whether outside providers work in the client’s own QuickBooks file as users, or receive copies of data.
• Tax return information, if the firm prepares returns. Section 7216 is stricter than the AICPA rules. Information furnished in connection with preparing a return is tax return information (Treas. Reg. §301.7216-1(b)(3)), and the regulation that lets one preparer pass it to another for auxiliary services without the taxpayer’s consent covers only a recipient “located in the United States” (Treas. Reg. §301.7216-2(d)(1)). A provider outside the US needs the taxpayer’s written consent first, in the form set out by Rev. Proc. 2013-14 for Form 1040 filers and Rev. Proc. 2008-35 for other returns, and for a Form 1040 filer the taxpayer’s SSN is masked unless the consent and safeguards in §301.7216-3(b)(4) are met. A firm that keeps books and prepares returns for the same client should treat this as part of the letter, not an afterthought.

In the firm’s agreement with the provider: confidentiality, the provider works only through the firm and never contacts the client, the provider’s access ends when the firm says so, and the provider’s scope matches the client’s scope, month for month. The clauses for that side are in bookkeeping subcontractor agreement. How a file moves under that arrangement is in how to subcontract a QuickBooks cleanup, and when subcontracting makes sense at all is on subcontract bookkeeping.

Reading a bookkeeping engagement letter before you sign

If you are the business owner, six questions decide most of what the letter is worth to you:

1. Does it name my accounts and the first month covered? If it says only “bookkeeping,” ask what happens to the months before the start date.
2. Is cleanup or catch-up included, or quoted separately? A low monthly fee on a file a year behind usually means a separate backlog bill.
3. What am I committing to provide, and by when? Those dates decide whether the firm’s dates are kept.
4. Who owns the QuickBooks subscription, and am I primary admin? You should be, and the letter should say you keep the file if you leave.
5. Does anyone outside the firm work on my books? A firm that uses outside help should tell you in the letter.
6. What does it cost to leave? Notice period, final invoice, and how fast the firm’s access is removed.

Common questions about engagement letters

Do engagement letters need to be signed?

They should be. A signature, or an emailed acceptance the letter asks for, is the evidence that the client agreed. Under the federal E-SIGN Act, a signature or contract “may not be denied legal effect, validity, or enforceability solely because it is in electronic form” (15 U.S.C. §7001(a)), so an e-signature is fine. Have it signed before any work starts.

Is an engagement letter legally binding?

Once both sides accept it, it is a contract, and it binds the way any services contract does under your state’s law. Whether a particular clause holds, a liability cap especially, is a state-law question for an attorney.

Who signs the engagement letter?

Someone at the firm with authority to commit it, and someone at the client with authority to commit the business: the owner, an officer, or a managing member. If the business has more than one owner, the letter should name who the firm takes instructions from.

How often should an engagement letter be updated?

Whenever the scope changes, with a new letter or a signed addendum, and many firms re-send it each year at the fee review. A letter from three years ago that lists two bank accounts does not describe a file that now has five.

What is a bookkeeper not allowed to do?

A bookkeeper without a CPA license cannot call themselves a CPA or issue a CPA’s audit or review report, which state accountancy laws reserve for licensed firms. Without a credential under Circular 230, they cannot represent a client before the IRS, apart from the narrow Annual Filing Season Program exception for returns they prepared and signed. They can keep the books, reconcile, run payroll and, with a PTIN, prepare returns. Put the line in the letter’s exclusions.

Where can I find a bookkeeping engagement letter template?

Professional bodies and practice software vendors publish them, and the AICPA has samples for its members. Ledgerbrook does not publish one: a template is only as good as its fit with your state’s law and your insurer’s terms, and it should be reviewed by an attorney before you send it. Use this post as the checklist for whichever template you start from.

Where Ledgerbrook fits

For a firm, Ledgerbrook is the provider the outside-help clause describes: QuickBooks Online cleanup, catch-up and monthly work, done as an accountant user in the client’s own file, under the firm’s name, with every question routed to the firm. Who does what is on white-label bookkeeping, and how a file moves from review to delivery is on bookkeeping for firms.

For a business owner whose new bookkeeper’s letter quotes the backlog separately, that backlog is a QuickBooks cleanup, priced per month and fixed before any work starts.

Before you send the next letter: if a client’s file has months that do not reconcile, scope the cleanup before the monthly fee starts. A free file review shows how many months need work, in writing, within 48 hours.