Section 9(2)(a) in Coking Coal Mines (Nationalisation) Act, 1972
(a)save as otherwise provided elsewhere in this act, no claim for wages, bonus, royalty, rate, rent, taxes, provident fund, pension gratuity or any other dues in relation to a coking coal mine or coke oven plant in respect of any period prior to the appointed day, shall be enforceable against the Central Government or the Government company;