India's central bank Wednesday let state-run banks provide extra expenditure on staff pensions and gratuities in installments over the next five years. India's nationalized banks recently re-opened the option of a pension for staff who had not opted for it earlier. The Indian Banks' Association, the representative body of the banking sector, had asked the Reserve Bank of India to let them amortize the additional expenditure. The RBI has let the state-run banks amortize the amount over the next five years, starting from the fiscal ending March 31. The banks will have to provide a minimum of one fifth of the total amount involved every year, it said.