(1) The expenditure in relation to income which does not form part of the total income shall be the aggregate of following amounts: —

(a) the amount of expenditure directly relating to income which does not form part of total income; and

(b) an amount equal to 1% of the annual average of the monthly averages of the opening and closing balances of the value of investment, income from which does not or shall not form part of total income.

(2) The amounts referred to in sub-rule (1) shall not exceed the total expenditure claimed by the assessee.