The scheme must provide that, in preparing a profit and loss account for the purposes of this Schedule, no changes may be made from the accounting policies used in preparing accounts for any earlier period relevant for those purposes, or in the methods of applying those policies, if the effect of the changes (either singly or taken together) would be that the amount of profits (or losses) differed by more than 5 per cent. from what would be that amount if no changes were made.

Sub-paragraph (1) above has effect subject to paragraph 19(2) above.