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Accounting and Bookkeeping Engagement Letters: What Every Letter Should Cover

10/6/2026

Most fee disputes, scope arguments and malpractice claims against small accounting firms trace back to one document: an engagement letter that was missing, out of date, or written for a different service. Tax engagement letters usually get attention because the season forces it. Letters for bookkeeping, financial statement and advisory work are where firms cut corners: a one-page template from years ago, a scope line that says "accounting services," and nothing about what happens when the client stops sending bank statements.

This post is a clause-by-clause checklist for non-tax engagements: monthly bookkeeping, payroll support, financial statement preparation, compilations, reviews and advisory work. It explains what each section should cover and why, and where professional standards require specific content. It is not a template and not legal advice. Have counsel familiar with your state review your final letters, and use the AICPA's own resources for the standards-required wording.

Why Non-Tax Work Needs Its Own Letter

A bookkeeping engagement letter has a different job from a tax return letter. A tax engagement ends with a filed return. A bookkeeping engagement is ongoing, depends on the client delivering information on time every month, and has no natural end point. That creates risks a tax letter does not address:

  • Scope creep. Bookkeeping clients assume "the accountant" handles payroll tax filings, sales tax, 1099s, cleanup of prior years and advice on the side. Unless the letter says otherwise, a court or a peer reviewer may read the relationship broadly.
  • Reliance on client data. The firm records what the client provides. If the letter does not say the firm is not auditing or verifying that information, a client whose employee embezzled through the books will argue the bookkeeper should have caught it.
  • Responsibility for decisions. Who approves journal entries, who signs checks, who has authority over bank accounts: these decide whether the firm is performing a service or acting as management.
  • Open-ended billing. Fixed monthly fees with no definition of a "normal" month invite disputes the first time the client brings in three months of shoeboxes.

Separate letters (or clearly separate schedules) for each service type keep the right terms attached to the right work. Many firms send one master agreement with a schedule for each service.

Where the Standards Require Specific Content

Some engagements carry mandatory engagement-letter requirements.

Compilations, reviews and preparation of financial statements

The AICPA's Statements on Standards for Accounting and Review Services (SSARS) cover preparing financial statements (AR-C section 70), compilations (AR-C section 80) and reviews (AR-C section 90). Each requires the accountant to agree the terms of the engagement with management or those charged with governance and to document them in an engagement letter or other written agreement.

For a compilation, AR-C 80 lists what the written agreement should include:

  • the objectives of the engagement;
  • the responsibilities of management;
  • the responsibilities of the accountant;
  • the limitations of the compilation engagement;
  • the applicable financial reporting framework; and
  • the expected form and content of the compilation report, with a statement that the report may differ from that in some circumstances.

AR-C 80 also requires the letter to be signed by both the accountant or firm and management or those charged with governance. The preparation and review sections have parallel requirements, and a review letter carries additional content because a review provides limited assurance. Use the current AICPA text for these elements rather than paraphrasing from memory, and check it whenever SSARS are amended.

Audit engagement letters fall under AU-C section 210, which requires the terms of an audit to be agreed and documented in an engagement letter or other written agreement. Audit letters are a specialized document and beyond this checklist, but the practice provisions below apply to them too.

Bookkeeping and other nonattest services for attest clients

Pure bookkeeping, where the firm does not prepare financial statements, is generally outside SSARS. But if the firm also performs an audit, review or other attest engagement for the same client, the AICPA Code of Professional Conduct's rules for nonattest services apply. Among other conditions, the firm must document its understanding with the client about the objectives of the nonattest engagement, the services to be performed, the client's acceptance of its responsibilities, the firm's responsibilities, and any limitations. The client must also take on management responsibilities and designate someone with suitable skill, knowledge or experience to oversee the services. A good bookkeeping letter documents all of this, so it is worth writing every bookkeeping letter as if the client might become an attest client later.

The Clause-by-Clause Checklist

1. Parties and effective date

Name the legal entity being served, not the owner personally, unless the owner is the client. Where several related entities are covered, list each one. State the effective date and, for recurring work, that the letter remains in effect until replaced or terminated.

2. Services in scope

This is the clause that matters most. Describe each service specifically:

  • Bookkeeping: which accounts are reconciled, how often, what system is used, and what deliverables the client receives (for example monthly reconciled ledger, trial balance, management reports).
  • Payroll support: whether the firm processes payroll, files payroll returns, makes deposits, or only reviews a third-party provider's output.
  • Financial statements: whether the firm prepares them, compiles them or reviews them, the framework (GAAP, tax basis, cash basis), and the periods.
  • Advisory: the defined project or the recurring meeting cadence, rather than open-ended "consulting."

3. Services out of scope

List what the firm is not doing: tax returns (if covered by a separate letter), sales and use tax filings, 1099 preparation, audit of the client's records, detection of fraud, cleanup of prior periods, legal or investment advice. A short exclusion list prevents most scope disputes. State that services outside the letter require a written amendment or a separate letter.

4. Client responsibilities

The client's side of the engagement, in plain language:

  • providing complete and accurate records by an agreed date each period;
  • management decisions and approvals, including approving adjusting entries and owning the books;
  • internal controls, safeguarding assets and preventing and detecting fraud;
  • designating a person with the skill to oversee the services;
  • compliance with laws and regulations that apply to the business; and
  • for financial statements, the selection of the framework and the content of the statements.

This section is where a firm protects itself if the client's data turns out to be wrong. It also keeps the firm on the right side of the line between service provider and management.

5. Firm responsibilities and limitations

Say what the firm will do, to what standard, and what it will not do. For bookkeeping and preparation work, state that the firm will not audit or verify the information provided and that the engagement cannot be relied on to detect errors, fraud or illegal acts. That is a factual description of the service, not boilerplate. If the firm discovers something significant, say how it will be communicated.

6. Access, authority and bank accounts

Spell out what system access the firm has and what it may do with it. A firm that can view bank feeds is in a different position from one that can initiate payments. If staff will sign checks, approve payments or hold credentials that move money, address it directly. Many firms decline those authorities entirely because of the independence and liability implications.

7. Timing and deliverables

Give the monthly or quarterly schedule: when the client delivers records, when the firm delivers results. Add what happens when the client is late: the deadline moves, and catch-up work is billed separately.

8. Fees and billing

The fee clause should match how the firm actually prices the work. For fixed monthly fees, define what a standard month includes (for example, a number of bank and card accounts and a transaction volume) and how work beyond it is priced. State billing frequency, payment terms, late-payment consequences and the firm's right to suspend work when invoices are unpaid. Our post on value-based billing for CPA firms covers designing fixed-fee scopes that hold up. Contingent fees are prohibited for certain attest clients under the AICPA Code, so check before agreeing to any fee tied to results.

9. Records and work papers

Distinguish the client's records (which belong to the client and must be returned) from the firm's work papers (which belong to the firm). Describe how and when client records are returned at the end of the engagement and how records requests will be handled. The AICPA Code and state board rules govern this area, so make sure the letter is consistent with them; a letter that promises less than the rules require does not override them.

10. Confidentiality and data security

State how client information will be protected, transmitted and stored, and whether the firm uses third-party service providers or cloud platforms that will hold client data. If staff use AI tools on client data, say so and describe the safeguards. Our post on AI governance policies for accounting firms covers the internal side. Make the letter consistent with the firm's written information security program.

11. Third-party use of financial information

If the client will give the financial statements or reports to a lender, investor or buyer, the letter should say so and should address how the firm's name may be used. A compilation or review report attached to statements is governed by the standards. Statements prepared without a report still need to be identified as such when they go to a third party.

12. Term, termination and withdrawal

Either party should be able to end a recurring engagement on written notice. Add the firm's right to withdraw immediately in specific circumstances: unpaid fees, failure to provide information, a request to act unethically, or discovery of an illegal act. State what happens to work in progress and final billing.

13. Dispute resolution and governing law

Whether disputes go to mediation, arbitration or court, and which state's law applies, is a legal and insurance question. Ask your professional liability carrier; many carriers have preferences or requirements about these clauses.

14. Signatures and annual renewal

Have the letter signed by a person authorized to bind the client and by the firm. For recurring engagements, review and re-sign each year, or at least when the scope or fees change. A letter from four years ago that describes services the firm no longer performs is almost as weak as no letter.

Common Mistakes Peer Reviewers and Claims Handlers See

  • No letter at all for small bookkeeping clients "because it's only a few hundred dollars a month."
  • Tax letter used for bookkeeping, so nothing addresses reliance on client data or management responsibilities.
  • Scope drift without amendment: the firm started doing payroll filings years ago, and the letter never caught up.
  • Unsigned letters, or letters signed by someone without authority to bind the entity.
  • Missing SSARS elements in compilation and review letters, a finding that comes up in peer review. Our peer review checklist covers the documentation reviewers expect.
  • No termination path, so firms keep doing unpaid work for clients they would like to drop. The post on handling difficult clients addresses the relationship side.

Making Engagement Letters Part of the Firm's System

The firms with the fewest disputes do not just have good letters. They have a process: no work starts until the letter is signed, letters are re-issued every year, scope changes trigger amendments, and someone owns the template library. That process belongs in the firm's written policies alongside client acceptance, workflow and billing.

The Tax Business Management Manuals bundle collects the firm's operating documentation in four manuals: the Tax Office Operations Manual, the Tax Business Personnel Manual, the Tax Business Marketing Manual and the Tax Business Expansion Manual. For firms building out their written policies, that set is a practical starting point. Practitioners who also want to understand the regulatory and data-security obligations behind the confidentiality clauses can look at Tax Practitioner Regulations, Penalties and Security.

Put the Letter and the Policy Behind It in Place

A good accounting engagement letter is specific about scope, clear about who is responsible for what, honest about the limits of the service, and backed by a firm process that keeps it current. Write separate terms for each service type, include the standards-required elements for financial statement work, and re-issue every year.

To document the office policies that make the engagement letter process stick, start with the Tax Business Management Manuals.

Frequently Asked Questions

What should a bookkeeping engagement letter include?

At minimum: the parties, a specific description of the bookkeeping services and deliverables, services that are excluded, the client's responsibilities (accurate records, management decisions, internal controls, oversight of the services), the firm's responsibilities and the limits of the service, timing, fees and what a standard month includes, records and work papers, confidentiality and data security, termination, dispute resolution, and signatures. The most important clauses are scope, exclusions and client responsibilities, because they decide most disputes. Have counsel review your final version.

Is an engagement letter required for bookkeeping services?

Professional standards do not always require one for bookkeeping performed for a non-attest client, but practically every firm should use one. Once financial statements are prepared, compiled or reviewed, the SSARS require a written agreement signed by the accountant and management. If the firm also performs attest work for the client, the AICPA Code requires documented understandings for nonattest services. Many professional liability carriers also expect signed engagement letters, and their absence weakens the firm's position in any dispute.

What does a compilation engagement letter have to contain?

AR-C section 80 requires the terms to be documented in an engagement letter or other written agreement covering the objectives of the engagement, management's responsibilities, the accountant's responsibilities, the limitations of a compilation, the applicable financial reporting framework, and the expected form and content of the compilation report, with a note that it may differ in some circumstances. The letter must be signed by the accountant or firm and by management or those charged with governance. Use the current AICPA text for these elements.

How is a CPA engagement letter for audits different?

Audit engagement letters fall under AU-C section 210 and must document the agreed terms of the audit, including the objective and scope, the auditor's and management's responsibilities, the financial reporting framework, and the expected form of the report. Audit letters often include additional provisions on access to information, representations and communication of findings. They are a specialized document, so firms usually maintain a separate audit template that is reviewed against the standards each year rather than adapting a bookkeeping letter.

How often should engagement letters be renewed?

For recurring work like monthly bookkeeping, re-issue and re-sign the letter at least once a year, and amend it whenever the scope, fees or people change. An annual renewal is also a natural time to reprice, confirm the client's designated contact, and update data-security and technology language. A letter that describes services the firm stopped performing, or omits ones it has added since, offers little protection when a dispute arises.

Can I use one engagement letter for tax and bookkeeping work?

You can use one master agreement, but each service needs its own terms, typically in separate schedules. Tax engagements end with filed returns and carry tax-specific provisions; bookkeeping is ongoing and depends on client data and management decisions; financial statement work carries required SSARS elements. Putting all of them under one generic scope line leaves the most important terms unclear. Separate schedules, signed together, keep each service's terms attached to that service.