GST Audit by the Department: Section 65, ADT-01 Notice, Timelines and Special Audit Under Section 66

A GST audit by the department under section 65 of the CGST Act starts with a notice in Form GST ADT-01 at least 15 working days in advance. The audit must be completed within three months of commencement (the Commissioner can extend it by up to six months), and the findings come to you in ADT-02 within 30 days of its conclusion. If tax is found short paid, the department follows up under section 73, 74 or 74A. A special audit under section 66 is different: an outside chartered or cost accountant nominated by the Commissioner audits the books, under a direction in ADT-03.

Sources checked: 21 October 2026

Facts checked on 21 October 2026 against sections 65 and 66 of the CGST Act and rules 101 and 102 of the CGST Rules on the CBIC tax information portal, and CBIC Instruction 03/2024-GST.

Key facts

Point	Departmental audit (s.65)	Special audit (s.66)
Who orders it	The Commissioner or an officer he authorises, by general or specific order	An officer not below Assistant Commissioner, with the Commissioner's prior approval
Who audits	Department officers	A chartered or cost accountant nominated by the Commissioner
Where	Your place of business or the tax office	—
Notice or direction	ADT-01, at least 15 working days ahead	ADT-03
Time to complete	3 months from commencement; extendable by up to 6 months with reasons	Report within 90 days; extendable by a further 90 days
Findings	ADT-02, within 30 days of conclusion	ADT-04
Hearing	Discrepancies may be put to you first (r.101(4))	Opportunity of being heard on its material (s.66(4))
Cost	—	Paid by the Commissioner (s.66(5))
Follow-up	Section 73, 74 or 74A if tax is short paid	—

What is a departmental GST audit?

It is a check of your books and returns by the department's own officers. Under section 65(1) and (2) the Commissioner, or an officer he authorises by general or specific order, may audit any registered person, at the person's place of business or in the officer's office. Under rule 101(1) the period audited may be a financial year, part of one, or several years.

How much notice will I get?

At least 15 working days, under section 65(3), in Form GST ADT-01 (rule 101(2)). Use the notice period to put them in order (see the checklist below) rather than waiting for the first visit.

How long can the audit take?

The audit must be completed within three months of commencement, and the Commissioner may extend that by up to six months, with the reasons recorded in writing (section 65(4)). "Commencement" is the later of:

• the date on which the records and other documents called for are made available, or
• the date the audit actually starts at the place of business.

So a delay in producing records can push the start date, and with it the end date.

Step	When
ADT-01 notice	At least 15 working days before the audit
Audit commences	Later of records made available and actual start at the place of business
Audit completed	Within 3 months of commencement (up to 6 more months if extended)
Findings in ADT-02	Within 30 days of the audit's conclusion

What do I have to provide?

Section 65(5) requires you to give the auditors the facilities needed to verify your books of account and other documents, to furnish the information they ask for, and to help complete the audit on time. A practical checklist:

1. Returns for the period (GSTR-1, GSTR-3B and the annual return), with reconciliations to your books.
2. Purchase records matched to the credit claimed.
3. Sales invoices, credit notes and e-way bills.
4. Stock records.
5. A short note on any position you took on rate, classification or credit, with the basis.

How are the findings communicated?

Before finalising, the officer may inform you of discrepancies noticed and consider your reply (rule 101(4)). Use that chance: answer each point with a reconciliation or a document.

The findings, your rights and obligations and the reasons for the findings are then given to you within 30 days of the conclusion of the audit (section 65(6)), in Form GST ADT-02 (rule 101(5)).

What happens if the audit finds tax short paid?

Under section 65(7), where the audit finds tax short paid, the officer may start action under section 73, 74 or 74A (section 74A was added by the Finance (No. 2) Act 2024). That usually means an intimation in DRC-01A or a show cause notice. See our guide to DRC-01A for what paying before a notice can save.

One related instruction is worth knowing. CBIC Instruction 03/2024-GST (14 August 2024) says that where an audit issue rests on an interpretation followed as a prevalent trade practice, the Zonal Chief Commissioner should refer it to the GST Policy wing or the Tax Research Unit, and it applies to ongoing audits too. If an objection concerns an industry-wide practice, it is worth asking our expert team whether this applies.

What is a special audit under section 66?

A special audit can be directed at any stage of scrutiny, inquiry, investigation or other proceedings. Under section 66(1), an officer not below Assistant Commissioner, with the Commissioner's prior approval, may direct you to get your records audited by a chartered accountant or cost accountant nominated by the Commissioner, where he considers that the value declared is not correct or the credit availed is not within normal limits.

• Direction: Form ADT-03; findings: Form ADT-04 (rule 102).
• Report: within 90 days, which may be extended by a further 90 days on application or for sufficient reason (section 66(2)).
• Hearing: you must be given an opportunity of being heard on material gathered in the special audit (section 66(4)).
• Cost: the Commissioner pays the cost of the audit (section 66(5)).

Getting help

Our GST audit and litigation support team helps you prepare reconciliations before ADT-01 visits, answer discrepancies under rule 101(4), and respond to any notice that follows. Our notice decoder explains common GST notices in plain language, and GST notices explained covers the other forms. To ask our expert team about an audit notice, book a consultation.