3In estimating the expenditure mentioned in paragraph 1 above which they will incur in respect of any financial year a local authority shall take into account—
(a)such additional sum as is in their opinion required—
(i)to cover expenses previously incurred;
(ii)to meet contingencies; and
(iii)to meet any expenses which may fall to be met before the money to be received from the sources mentioned in paragraph 1 above in respect of the next following financial year will become available; and
(b)any means by which any part of that expenditure may otherwise be met or provided for.