No part of a student's covenant income or grant income shall be disregarded under paragraph 13 of Schedule 2 and any F1other income to which sub-paragraph (1) of that paragraph applies shall be disregarded thereunder only to the extent that the amount disregarded under regulation 39(2)(b) (calculation of covenant income where a contribution is assessed) or, as the case may be, 40(1)(c) (covenant income where no grant income or no contribution is assessed) is less than F2£20.