(1)In determining the reduced rate of tax by reference to which arrangements for any year of assessment are made under subsection (1) of section 343 of the Taxes Act (building societies) the Board shall, notwithstanding anything in the proviso to that subsection, leave out of account any information which is obtained by them after the beginning of that year other than information relating to changes in the rates of tax or personal reliefs for that year or to changes in the general level of incomes.
(2)This section has effect for the year 1980-81 and subsequent years of assessment.