Tax Audit is conditional audit, conducted under the regulations of Income Tax Act. The Act states that if the turnover of any enterprises is more than 10 crore, and in case of professionals if the value of services is more than Rs. 50 lacs then they have to get their books of accounts audited by a Chartered Accountant.
The only exemption here is if the enterprise has opted for the Presumptive Taxation scheme, then the entity does not have to get its books of accounts audited. But this scheme is not applicable for companies, which means for every company whose turnover crosses Rs. 10 crore for the financial year, has to get its books of accounts audited.