70.  Change in the constitution of a firm.-

(1)   Where, at the time of making an assessment on a firm under section 62, 63 or 65 it is found that a change has occurred in the constitution of the firm, the assessment shall be made on the firm as constituted at the time of making the assessment, but the income of the firm shall be apportioned among the partners who were entitled to receive it and, where the tax assessed upon a partner cannot be recovered from him, it shall be recovered from the firm as constituted at the time of making the assessment.

(2)   The provisions of sub-section (1) shall, so far as may be, apply to the determination of total income and the tax payable under section 59 or section 59A as they apply to an assessment under section 62, 63 or 65.