(3)For the purposes of this section,—(a)where in relation to a tax year, an assessment is made for the first time under section 279, the assessment so made shall be regarded as a regular assessment;(b)tax on total income as determined under section 270(1) shall not include the additional income-tax, if any, payable under section 267;(c)tax on the total income determined under such regular assessment shall not include the additional income-tax payable under section 267.
