Presumptive taxation rules for resident businesses and professionals set turnover limits, audit triggers, and five-year compliance restrictions. Special provision applies to computation of profits and gains of certain resident assessees on a presumptive basis, overriding contrary provisions to the extent inconsistent with this scheme. For eligible assessees and specified professionals, profits are deemed at prescribed percentages of turnover or gross receipts, subject to turnover, cash-receipt, and residency conditions. Goods carriage business is covered separately for an assessee owning not more than ten goods carriages, with income computed per vehicle and per month, or on the basis of higher actual profit if claimed. The provision also sets out threshold conditions, books and audit requirements, treatment of losses and deductions, written down value, a five-year bar on re-entering the regime, and key definitions.