Engagement Letter explained: this guide covers what it means, who it applies to, the step-by-step process, documents required, fees, due dates and penalties in India — so you can stay compliant with confidence and avoid costly mistakes.
Appendix IX carries two sample engagement letters — one for a Form 3CA appointment and one for Form 3CB, which adds the audit of the financial statements to the scope of work.
From the ICAI Guidance Note on Tax Audit (Revised 2026), the Eleventh and, by ICAI's own statement, concluding edition under the Income-tax Act, 1961. The samples are drafted around section 44AB and rule 6G; for tax years under the Income-tax Act, 2025 the scope clause must name section 63 and Form No. 26 under rule 47 of the Income-tax Rules, 2026 instead.
Two letters, two scopes
Appendix IX, cited at paragraph 9.23, gives Sample Engagement Letters for Tax Audit. The first is for an individual assessee reporting in Form 3CA; the second is for Form 3CB. The addressee differs — "" in the first, "" in the second — and so does the scope:
| Scope of work | Form 3CA letter | Form 3CB letter |
|---|---|---|
| Audit of the general purpose financial statements — balance sheet as at the year end and the profit and loss account for the period | — | Clause 1.1 |
| Issue the audit report and certify the Form 3CD particulars | Clause 1.1 — report in Form No. 3CA as specified under clause (a) of sub-rule (1) of rule 6G | Clause 1.2 — report in Form No. 3CB as specified under clause (b) of sub-rule (1) of rule 6G |
Using the Form 3CA sample where Form 3CB is the correct report leaves the audit of the financial statements out of the agreed scope — and that audit is precisely what a Form 3CB engagement requires, since there is no other audit to rely on. Choose the sample from the rule 6G route first, not from the assessee's constitution.
The opening recitals
Both letters open the same way. The auditor refers to the assessee's letter of appointment by date, and states that the engagement letter "confirms the understanding of mutual responsibilities upon which (Membership Number — ) has been engaged to perform the following services".
Two drafting points follow from that sentence. The membership number appears in the body, not only in the signature block; and the letter is framed as a record of mutual responsibilities — which is why the management responsibility clause carries as much weight in this engagement letter as the auditor's own.
Auditor's responsibility — clause 2
| Clause | Content |
|---|---|
| 2.1 | The audit will be conducted in accordance with the Standards on Auditing issued by the ICAI, which require compliance with ethical requirements and planning and performing the audit to obtain reasonable, rather than absolute, assurance about whether the particulars in Form No. 3CD are appropriate |
| 2.2 | Because of the inherent limitations of an audit, including the possibility of collusion or improper Management override of controls, there is an unavoidable risk that material misstatements due to fraud or error may occur and not be detected, even though the audit is properly planned and performed |
| 2.3 | The audit includes an examination of evidence on a test check basis, having regard to the materiality of the items involved, assessed on both quantitative and qualitative factors |
| 2.4 | Where specialised knowledge or expertise beyond accounting or auditing is needed, the auditor may engage an expert under SA 620; the expert works under his direction and supervision and he remains responsible for the audit opinion expressed |
| 2.5 | The audit will be carried out under section 44AB, the Income-tax Rules, 1962, this Guidance Note and CBDT or Ministry of Finance notifications, with the objective of expressing an opinion in Form No. 3CA on the correctness of the particulars given in Form No. 3CD |
| 2.6 | Pursuant to ICAI requirements, the auditor must update certain relevant details of the operations of the Entity on the UDIN Portal for generating the UDIN, which is required to be stated on the reports issued |
Stating in the engagement letter that fraud may go undetected despite a properly performed audit is not defensive boilerplate — it is the assurance level the client is buying, written down before the work starts. Read with clause 3.3's release from liability for misrepresentations by Management and clause 8's limitation of damages, it sets the expectation that the tax audit is a reasonable assurance engagement on the Form 3CD particulars, not a guarantee of their accuracy.
The sixteen clauses of the engagement letter
- Scope of Work
- Auditor's Responsibility
- Management's Responsibility
- Matters to be Communicated to Those Charged with Governance — significant findings, views on significant qualitative aspects of accounting practices, policies, estimates and disclosures, significant matters concerning related parties, and the written representations requested
- Working Papers
- Confidentiality of Information
- Independence
- Limitation of Damages
- Indemnification
- Fees
- Invoicing
- Governing Law, Jurisdiction & Dispute Resolution
- Anti-Money Laundering & Prevention of Corruption
- Entire Agreement
- End-Use
- Termination of Agreement
Clause 12 fixes both the law and the forum: the agreement is governed by the laws of India; the parties will attempt to resolve a dispute by discussion and negotiation before commencing legal proceedings; and all disputes are deemed to have arisen at the place where the office of the auditor is situated, and only courts having jurisdiction over that place shall determine them.
Fees, invoicing and termination
- Fees are stated exclusive of GST, with GST and other statutory liabilities charged separately, and bills payable promptly on presentation. Direct out-of-pocket expenses necessarily incurred — conveyance, external disbursements, outstation travel, lodging and boarding — are billed at cost and reimbursed.
- Invoicing: expense invoices as soon as possible after they are incurred; professional fee invoices after completion or on a progressive basis. Unless specifically waived, interest is charged on amounts outstanding beyond 30 days from the invoice date, and the auditor may suspend the Services until all amounts due are paid in full.
- Termination: either party may terminate on 30 days written notice for a material breach not remedied within 5 business days of a notice. The auditor may then invoice on the basis of time spent at agreed hourly rates up to the amount of the fixed fee, plus out-of-pocket expenses. He may also terminate on changes to laws, regulations, or the shareholding or group structure that would render the services illegal or in conflict with independence or professional rules.
End-use is clause 15: the report and opinion are solely for the purpose specified in the Scope of Work. If the client intends to publish or reproduce the opinion, or refer to the auditor in a document containing other information, it agrees to provide a draft for the auditor to read and obtain his approval for inclusion of the audit report before it is printed and distributed.
The acknowledgement
The engagement letter closes: "If these arrangements are acceptable, please sign one copy of this letter and return it to me." The acknowledgement block is completed on behalf of the entity in terms of the approval dated ___ by the Audit Committee / Board of Directors / Management / Authorised Representative, with signature, name and designation, date and place.
The reference to an approval date matters: the acknowledgement is not merely a countersignature but a record that the engagement was authorised by a competent organ of the client — the same authority that appointed the auditor.
Audit checklist
- Pick the engagement letter sample by the rule 6G route — Form 3CA or Form 3CB.
- For a Form 3CB engagement, include the audit of the financial statements in the scope.
- State the previous year and assessment year and refer to the appointment letter by date.
- Include the membership number in the body.
- Retain the reasonable-assurance and inherent-limitation clauses.
- Keep the SA 620 expert clause where specialist input is likely.
- State the fee exclusive of GST, and the out-of-pocket reimbursement basis.
- Obtain the signed acknowledgement with the approval date before starting fieldwork.
- Update the statutory references when reporting under the Income-tax Act, 2025.
Common mistakes
- Using the Form 3CA sample for a Form 3CB engagement.
- Starting fieldwork before the acknowledgement is signed and returned.
- Omitting the previous year and assessment year, so the engagement letter serves indefinitely.
- Dropping the end-use clause, leaving the report free to be reproduced elsewhere.
- Leaving the fee inclusive of GST and the expense basis unstated.