Section 39(1)(f) in The U.P. Zamindari Abolition and Land Reforms Act, 1950
(f)where royalties are payable on account of mines and minerals the average income on account of royalties calculated on the basis of the annual returns filed by the intermediary for the assessment of cess or income-tax during the period of twelve agricultural years preceding the agricultural year in which the date of vesting falls or any shorter period for which such returns have been filed;