Audits differ by who demands them. Some are required by law (statutory, tax, cost, secretarial), some by a regulator or lender (concurrent, stock), and some by the board or management (internal, forensic, IT). The auditor's qualification and the report also change with the type.
Facts checked: 9 October 2026. Thresholds change by notification, so confirm the current figure before accepting an engagement.
Quick view
| Type | Required by | Law or source | Performed by |
|---|---|---|---|
| Statutory | Law | Companies Act 2013, ss.139-143 | Chartered accountant (firm) |
| Tax | Law | Income-tax Act, s.44AB | Chartered accountant |
| Internal | Law for some companies, else the board | Companies Act s.138 | CA, cost accountant, or other professional |
| Concurrent | Regulator or bank | RBI directions | CA firm |
| Stock | Lender | Sanction terms | CA firm |
| GST | Law, in a limited form | CGST Act | Self-certified reconciliation |
| Cost | Law, for notified companies | Companies Act s.148 | Cost accountant |
| Secretarial | Law, for notified companies | Companies Act s.204 | Practising company secretary |
| Forensic | Court, regulator or board | No single law | Forensic specialist, often a CA |
| System/IT | Management or regulator | Sector rules | IT auditor (CISA, DISA) |
| Special purpose | Contract or law | SA 800 series | CA |
One paragraph each
Statutory audit. Annual audit of a company's financial statements, giving an opinion on true and fair view. The members appoint the auditor. See what is statutory audit.
Tax audit. Required under section 44AB when turnover, receipts or the presumptive-scheme position cross prescribed limits. The CA reports in Form 3CA/3CB with Form 3CD. Read the complete section 44AB guide.
Internal audit. An ongoing review of controls and processes, reporting to the audit committee or board. Section 138 and Rule 13 make it mandatory for listed companies and for larger unlisted ones based on paid-up capital, turnover, borrowings or deposits. Details are in the internal audit resource and the report format guide.
Concurrent audit. Real-time checking of transactions as they happen, common in banks under RBI instructions, and a separate engagement from the year-end statutory audit. See the bank audit guide.
Stock audit. A lender asks a CA to verify stock, receivables and drawing power against the sanctioned limit. The requirement comes from the bank's sanction terms, not from a statute.
GST audit. The old departmental and professional GST audit under the CGST Act was replaced from FY 2020-21 by a self-certified reconciliation statement (GSTR-9C) for registered persons above the prescribed turnover. The department can still audit under section 65.
Cost audit. Required under section 148 of the Companies Act for specified industries above prescribed turnover and net worth limits, performed by a cost accountant.
Secretarial audit. Section 204 requires it for listed companies and certain large companies. A practising company secretary reports on compliance with company law and related laws.
Forensic audit. An investigation of suspected fraud, tracing funds and preserving evidence. No single statute defines it; triggers include a court order, a regulator, a lender or the board. The forensic audit guide covers method.
System (IT) audit. Review of IT general controls, access, change management and data integrity. Regulators in banking and insurance prescribe it for their entities.
Special purpose audit. An audit of a single statement, schedule or compliance framework, for example a grant utilisation certificate, under SA 800 or SA 805.
Scenario
A mid-size manufacturer with a March year-end typically sees four audits in one cycle: the statutory audit, a tax audit, a bank stock audit, and an internal audit if the size tests are met. Each has a different report, a different addressee and a different deadline, so teams do not reuse one working file across them without checking scope.
Frequently asked questions
Which audit is mandatory for every company?
The statutory audit under the Companies Act, 2013. Others depend on size, sector or a lender's terms.
Can the same CA do the statutory and internal audit?
Not for the same company. Section 144 bars the statutory auditor from providing internal audit services to the company.
Is a tax audit a type of statutory audit?
It is required by statute, but it is a separate report under the Income-tax Act. See the difference between internal, statutory and tax audit.
Sign the right engagement terms for each: use the engagement letter template.
Statutory facts on this page are checked against their sources, and the page says where it relied on secondary reporting. How we verify · Report an error