Method of accounting controls business income computation, with notified standards and account rejection for non-compliance. Income under the heads of profits and gains of business or profession and income from other sources is computed according to the method of accounting regularly employed by the assessee, either cash or mercantile. Different systems may be followed for different businesses or sources of income. The Central Government may notify Income Computation and Disclosure Standards, and the Assessing Officer may reject the accounts where they are incorrect, incomplete, inconsistently followed, or not compliant with notified standards.