(4)When any sum payable under this section in respect of the income of such business or profession assessed on the predecessor,––(a)for the tax year in which the succession took place up to the date of succession; or(b)for the tax year preceding the year in which the succession took place,cannot be recovered from him, the Assessing Officer shall record a finding to that effect and the sum payable by the predecessor shall thereafter be payable by and recoverable from the successor, and the successor shall be entitled to recover from the predecessor any sum so paid.
