(1) The profits and gains arising from a construction contract or a contract for providing services, shall be determined on the basis of percentage of completion method, subject to provisions of sub-section (2), as per the income computation and disclosure standards notified under section 276(2).

(2) For the purposes of sub-section (1), the profits and gains arising from a contract for providing services shall be determined—

(a) on the basis of project completion method, if the duration of such contract is not more than ninety days;

(b) on the basis of straight-line method, if the contract involves indeterminate number of acts over a specified period of time.

(3) For the purposes of percentage of completion method, project completion method or straight-line method under this section, —

(a) the contract revenue shall include retention money;

(b) the contract costs shall not be reduced by any incidental income in the nature of interest, dividends or capital gains.