Can Banking Company or Financial Institution withdraw the option of availing actual credit or 50% credit anytime in the financial year?

According to Rule 38 of Central Goods and Service Tax Act, Banks, financial institutions and non banking financial companies (NBFC) engaged in business of deposits, extending loans or advances have an option to avail an amount equal to fifty per cent of the eligible input tax credit on inputs, capital goods and input services in that month or to take Input tax credit only on purchases made for selling taxable or zero rated goods or services and leave out the tax paid on purchases made for exempted supplies. Option once exercised can not be changes during the financial year.