There is not much difference between audit and assurance. Assurance includes limited reviews performed under SRE 2400/2410. Tax audit is similar to any other audit if we issue report under form 3CB since we opine on true and fairness of financial statements. In case of Tax audit where audit is performed under any othere statue, we do not opine again on the financial statements and issue report only on true and correctness of form 3CD.
SA/SRS are the guidance for doing any audits including tax audit under 3CB scenario. We refer in our reports also that audit is performed in accordance with SA guidance. It is mandatory to follow SA in performing audits and issuing audit reports. In case of other tax audits, please refer guidance note on tax audit issued by ICAI.
Regards,
Yogesh Singhal