Section 13(2)(iv) in The Coal Bearing Areas (Acquisition And development) Act, 1957
(iv)interest on any such expenditure referred to in clauses (i), (ii)and (iii) as has actually been incurred [up to] [Substituted by Act 51 of 1957, Section 6, for "during the period commencing from the date of the lease and ending with" (w.e.f. 12-6-1957)] the year in which the rights under the lease are acquired, interest being calculated in the following manner, that is to say,--