A special audit is a distinct statutory process
Section 66 of the CGST Act permits the stated officer, with prior Commissioner approval and in the specified circumstances, to direct a registered person's records to be examined by a nominated chartered accountant or cost accountant. Rule 102 uses GST ADT-03 for the direction and ADT-04 for communicating findings. This guide was checked on 28 October 2026. It concerns special audit, rather than the separate departmental-audit ADT-01/02 process or a private annual audit engagement. ICAI GST bare law, April 2026: section 66(1)–(4) and Rule 102.
Review authority, reasons and the nominated professional
Subsection (1) refers to an officer not below Assistant Commissioner rank, the nature and complexity of the case, revenue interest and the stated concerns about declared value or credit limits. The direction is in writing with prior Commissioner approval, and the professional is nominated by the Commissioner. A company's existing statutory auditor is not automatically the nominated special auditor. Preserve the actual ADT-03, scope, authorisation evidence and communication record; a generic request for documents should not be relabelled as a special-audit direction without checking its basis. ICAI GST bare law, April 2026: section 66(1)–(4) and Rule 102.
Keep the report clock and extension separate
Subsection (2) requires the nominated professional's signed and certified report within ninety days. The Assistant Commissioner may extend by a further ninety days on the stated application or reasons. An extension is not created by simply asking for it. Determine and document the legally applicable starting event and communicated deadline for the actual direction. The date examples below stipulate an accepted day-zero event and exclude that day; they do not decide disputed service or invent an automatic holiday adjustment. ICAI GST bare law, April 2026: section 66(1)–(4) and Rule 102.
Build a source-to-finding evidence file
Organise sales, valuation, credit, reversals and other records by the actual scope. Tie each extract to the general ledger, returns and source documents. Keep explanatory differences distinct from admitted errors: a credit variance alone is not a concluded demand. Preserve the auditor's information requests, delivery dates, versions and unresolved queries. Where the same invoice appears in multiple extracts, use a unique identifier to prevent repeated proposed adjustments in the reconciliation. ICAI GST bare law, April 2026: section 66(1)–(4) and Rule 102.
An existing audit does not prevent this process
Subsection (3) expressly allows the special-audit provision to operate despite an audit under another provision of the Act or another law. Existing audit reports remain useful evidence but do not, by themselves, defeat a valid direction. Subsection (4) requires a hearing opportunity for special-audit material proposed to be used against the taxpayer. Obtain the adverse material, explain factual and legal differences and preserve the response. Do not treat ADT-04 as proof that every observation has already become an enforceable tax determination. ICAI GST bare law, April 2026: section 66(1)–(4) and Rule 102.
Close report, findings and further proceedings separately
Keep a completion register for the professional's report and the taxpayer's findings communication; these are different events. Track the current statutory route and period for any later determination rather than copying a superseded demand-section reference. The scope of this article is the direction, report and response file; it does not prescribe an interest rate, assess tax on an unexplained variance or promise that findings automatically close all proceedings. Any payment decision needs a supported issue-wise calculation and applicable procedure. ICAI GST bare law, April 2026: section 66(1)–(4) and Rule 102.
Applicable primary references
ICAI GST bare law, April 2026: section 66(1)–(4) and Rule 102
Six worked illustrations
All facts and amounts below are fictional. Assumptions describe the model, not additional statutory rules.
Illustrative example 1: Ninety-day calendar model
Assume a legally accepted day-zero date of 1 April 2026 and a ninety-calendar-day report model excluding that day. The resulting endpoint is 30 June 2026. This is an arithmetic illustration, not a finding that every direction starts on its printed date.
Illustrative example 2: Full further extension
On the preceding assumptions, a duly granted further ninety days takes the model endpoint from 30 June to 28 September 2026. Total model period is 180 days; an extension request alone does not establish that result.
Illustrative example 3: Remaining time before the original endpoint
Using the same day-zero date, assume the review date is 15 June 2026. Seventy-five days have elapsed and fifteen remain in the original ninety-day model. Plan outstanding evidence without assuming an application will suspend the clock.
Illustrative example 4: Quantified difference is not automatically demand
Assume credit per one reconciled extract ₹15,00,000 and the comparison population ₹11,00,000. The ₹4,00,000 difference is a research population. Its tax consequence depends on invoices, periods, eligibility, reversals and the applicable law; do not book a ₹4,00,000 demand solely from subtraction.
Illustrative example 5: Remove an overlapping invoice observation
Assume two proposed issue schedules each contain the same ₹1,00,000 credit item, with distinct other items ₹2,00,000 and ₹3,00,000. The unique review population is ₹6,00,000, not ₹7,00,000. This reconciliation prevents duplication without deciding whether any item is disallowable.
Illustrative example 6: Reconcile reporting headroom
Assume the original accepted report endpoint is 30 June and the report is actually delivered on 25 June 2026. The delivery precedes that model endpoint by five days. Preserve actual delivery evidence, not merely the internal approval date of the draft.
Ten-step verification table
| Step | Action | Evidence |
|---|---|---|
| 1 | Identify the process | Section 66 and ADT-03 rather than another audit route |
| 2 | Check officer authority | Rank, prior approval and written direction evidence |
| 3 | Verify the nominated professional | Commissioner nomination and actual scope |
| 4 | Establish the report calendar | Supported starting event and ninety-day endpoint |
| 5 | Monitor any extension | Application, reasons and actual grant |
| 6 | Reconcile source populations | Ledger, returns, invoices and scope-specific extracts |
| 7 | Control request delivery | Versioned documents and receipt evidence |
| 8 | Review adverse material | Issue-wise facts, legal position and duplicate detection |
| 9 | Preserve hearing and findings records | Response and ADT-04 communication |
| 10 | Separate later determination | Applicable current procedure, amounts and independent deadlines |
Sixteen practitioner FAQs
1. Is special audit the same as departmental audit?
No. Section 66 and Rule 102 use their own authority and forms.
2. Which direction form does Rule 102 name?
GST ADT-03.
3. Which findings form does the rule name?
GST ADT-04.
4. Can every officer independently issue the direction?
Apply the subsection (1) rank and prior-approval conditions.
5. Who nominates the professional?
The Commissioner under the statutory arrangement.
6. Is the existing statutory auditor automatically selected?
No. Verify the actual nomination.
7. What report period does subsection (2) specify?
Ninety days, with the stated possible further extension.
8. Is another ninety days automatic?
No. Retain a supported grant under the provision.
9. Can the registered person seek the extension?
The proviso contemplates the stated application by the taxpayer or nominated professional, as well as the specified reasons.
10. Do these examples decide disputed starting dates?
No. They stipulate an accepted day-zero event.
11. Does an existing Companies Act audit by itself bar special audit?
Subsection (3) expressly addresses audits under other law.
12. Does a numerical credit mismatch itself prove ineligibility?
No. Investigate the source, period and applicable conditions.
13. Should duplicate invoice observations be counted twice?
No. Reconcile unique items before evaluating their consequences.
14. Must proposed adverse material receive a hearing opportunity?
Subsection (4) provides that protection within its scope.
15. Is ADT-04 automatically a final demand for every observation?
Do not conflate findings with the separate statutory determination process.
16. What evidence proves report delivery?
The actual submitted report and reliable delivery or receipt record.
Conclusion
Verify the special-audit direction, nominated professional and report timeline, then reconcile findings to source records before responding to adverse material.