A tax audit is not the same as a regular financial audit — it is a specific examination required under the Income-tax Act once a business or profession crosses prescribed thresholds, or in certain other situations. It is conducted by a chartered accountant and reported in standard forms. Here's who needs one, the forms involved, and why getting it right matters.
Reviewed by CA Harika Chebolu, FCA · Last updated 2026-06-15
Quick answer
A tax audit under Section 44AB is a chartered accountant's examination of your books, required once you cross certain turnover or receipts limits. Here's when it applies and what the forms involve.
The most common trigger is turnover or gross receipts crossing the limit prescribed for your kind of activity — there are separate thresholds for businesses and for professions. The business threshold is relaxed where cash transactions are small, reflecting the law's push towards digital payments. A tax audit can also be triggered in other circumstances, such as declaring income below the presumptive rate while your total income exceeds the basic exemption limit. Because the exact figures depend on your activity and your cash proportion, confirm the threshold that applies to you before assuming you are outside it.
A tax audit must be carried out by a practising chartered accountant. The CA examines your books of account and supporting records, checks that they reflect a true and correct picture, and reports particulars required under the law. This is an independent professional verification — the auditor is not simply filling in numbers you supply but forming an opinion and reporting prescribed details. Choosing your auditor early and giving them clean, complete records makes the process far smoother.
The audit report is filed in a standard format. Form 3CA is used where the accounts are already required to be audited under another law, and Form 3CB is used where they are not. In both cases the detailed statement of particulars is given in Form 3CD, which captures information about the business, method of accounting, deductions, payments, loans and a range of other items. The 3CD is detailed and specific, so the supporting data needs to be organised well in advance.
The tax audit report is filed electronically by the chartered accountant and then accepted by the taxpayer on the income-tax portal. The audit report has its own due date, which falls before the return-filing due date for taxpayers subject to audit, so the sequence matters: the report comes first, the return after. Missing the audit deadline can knock out the later return timeline too, so plan backwards from the report date rather than the return date.
Failing to get a tax audit done when required, or not filing the report on time, can attract a penalty linked to your turnover or receipts subject to a ceiling, unless you can show reasonable cause. Beyond the penalty, an unaudited or late position can complicate your return and invite questions. The simplest protection is to assess early whether you are likely to cross the threshold and engage an auditor in good time rather than at the deadline.
Businesses and professionals whose turnover or gross receipts cross the prescribed limit need a tax audit , as do some others — for example, those declaring income below the presumptive rate while their total income exceeds the basic exemption limit. The thresholds differ for business and profession and depend on your cash proportion, so confirm the figure that applies to you.
Form 3CA is used where your accounts are already audited under another law, and Form 3CB where they are not. In both situations the detailed particulars are reported in Form 3CD, which accompanies whichever of 3CA or 3CB applies.
You can face a penalty linked to your turnover or receipts, subject to a ceiling, unless you show reasonable cause , and a late audit report can disrupt your return-filing timeline too. Since the audit report is due before the return, plan backwards from the report date.
Wondering whether you cross the tax-audit threshold this year? Write to the firm and we'll check your turnover and cash mix and handle the audit if you need one.