Audit that is required to be conducted by every company registered under companies act 1956.There is no turnover creteria for this even with zero turnover company needs to get it accounts audited as per section 224
Tax audit:
tax audit that is to be conducted under provisions of income tax act. As per section 44AB of IT act, 1)professional gross receipts exceeds 25 lakhs in previous year 2)turnover of business exceeds 1 crore in previous year is mandatorily required get its books of accounts audited