# What is an engagement letter? > An engagement letter is the written agreement that sets out what a firm will do for a client, for how much, and what it will not do. Why firms use one. Source: https://learn.ynteractive.com/content/glossary/engagement-letter · Updated 2026-10-02 · Free from Stepthrough (https://learn.ynteractive.com) [Business](https://learn.ynteractive.com/content/glossary#topic-business) · [AI glossary](https://learn.ynteractive.com/content/glossary) Quick answer An engagement letter is a written agreement between a professional firm, such as a law, accounting or consulting practice, and a client. It states what work the firm will do, what it will not do, how it will charge, and how each side can end the relationship. Last updated October 2, 2026 Updated October 2, 2026 · By [Robert Breen](https://learn.ynteractive.com/content/about) ## Why it matters for a small business Most client frustration comes from mismatched expectations, and the letter is where you prevent them. If the firm agrees to file a complaint but not to handle an appeal, saying so up front avoids a painful conversation later. The same goes for who the client is, who pays, and how fast the firm will normally reply. For regulated professions, the letter may also be required or shaped by professional rules, and the exact contents vary by place. This glossary entry is a general explanation, not legal advice. If you need a letter drafted, ask a licensed attorney or follow the template your professional association or insurer supplies. ## In a real lesson: Reply Faster to a Client Asking for a Case Update: ChatGPT for Small Law Firms The [Reply Faster: Client Case Updates lesson](https://learn.ynteractive.com/content/chatgpt-client-case-update-email-law-firm) shows what happens after a letter is signed, not the letter itself. In it, Owen is a paralegal at Harbor Street Law, a made-up firm. His client Carla, a florist, is suing an event hall over an unpaid contract of $8,400. Several of the firm's facts read like the practical rules a good engagement letter sets. The firm does not discuss case details or accept evidence by text message. Screenshots belong in the secure client portal. The firm gives no predictions and no legal advice by email, and a lawyer can call to talk through questions. The lesson never mentions an engagement letter, so we don't know what Harbor Street's says. But rules like these work best when the client agreed to them at the start. In the reply, Owen restates them kindly, and ChatGPT checks each promise against the facts before he sends. [Try this lesson free](https://learn.ynteractive.com/modules/law-case-update-reply) or [read the step-by-step guide](https://learn.ynteractive.com/content/chatgpt-client-case-update-email-law-firm). ## Common confusions ### Engagement letter vs retainer The letter is the agreement. A [retainer](https://learn.ynteractive.com/content/glossary/retainer) is money, or an ongoing arrangement, a client pays under it. A letter can exist with no retainer, and a retainer should be covered by a letter. ### Engagement letter vs contract It is a kind of contract, usually shorter and written in plainer language. Whether it is legally binding depends on its terms and your jurisdiction, so a lawyer should review yours. ## Tips - State the scope in a sentence a client could repeat back to you. - List what is excluded as clearly as what is included. - Cover communication: which channels you use, and which you do not. ## Related terms [Retainer](https://learn.ynteractive.com/content/glossary/retainer) · [Billable hours](https://learn.ynteractive.com/content/glossary/billable-hours) · [Conflict check](https://learn.ynteractive.com/content/glossary/conflict-check) · [Legal information vs legal advice](https://learn.ynteractive.com/content/glossary/legal-information-vs-legal-advice) · [Client portal](https://learn.ynteractive.com/content/glossary/client-portal) · [Late fee](https://learn.ynteractive.com/content/glossary/late-fee) ## More Business terms [Estimate, quote and bid](https://learn.ynteractive.com/content/glossary/estimate-vs-quote) · [Executive summary](https://learn.ynteractive.com/content/glossary/executive-summary) · [Expense categorization](https://learn.ynteractive.com/content/glossary/expense-categorization) · [Expense reimbursement](https://learn.ynteractive.com/content/glossary/expense-reimbursement) ## Where you use it: free lessons - [Reply Faster to a Client Asking for a Case Update: ChatGPT for Small Law Firms](https://learn.ynteractive.com/content/chatgpt-client-case-update-email-law-firm) (ChatGPT, 10 min) - [Turn a Client Meeting into Action Items and a Follow-Up Email (Accounting Firms)](https://learn.ynteractive.com/content/chatgpt-client-meeting-recap-accounting-firm) (ChatGPT, 9 min) - [A Claude Project for Your Accounting Firm: Fee Schedule, Engagement Terms and Tone](https://learn.ynteractive.com/content/claude-project-accounting-firm-fee-schedule) (Claude, 9 min) - [Turn a Client Intake Call into Next Steps and a Conflict-Check List (Law Firms)](https://learn.ynteractive.com/content/chatgpt-client-intake-call-summary-law-firm) (ChatGPT, 9 min) ## Prompt templates that use it [Engagement fee increase letter prompt](https://learn.ynteractive.com/content/prompts/engagement-fee-increase-letter-prompt) · [Law firm consultation follow-up email prompt](https://learn.ynteractive.com/content/prompts/consultation-follow-up-email-prompt) ## Frequently asked questions **Does every client need an engagement letter?** Many firms use one for every client because it protects both sides. Whether yours must is a question for your professional rules and, for legal work, a licensed attorney. **Can AI write my engagement letter?** It can draft a starting outline, but it can get the law wrong and does not know your rules. Have a licensed professional review any letter before a client signs. [All AI glossary terms, A to Z](https://learn.ynteractive.com/content/glossary) · [Free prompt templates](https://learn.ynteractive.com/content/prompts)