Concessional corporate tax option: concessional rate requires forgoing specified deductions and is irrevocable once exercised. A domestic company may elect a concessional corporate tax regime by prescribed option, accepting a concessional tax rate while forgoing specified deductions and incentives; carry-forward losses and unabsorbed depreciation attributable to those disallowed deductions cannot be set off. The option is irrevocable once exercised, lapses on non compliance for that and subsequent years, and includes limited modifications for IFSC units and a Board-authorised guideline mechanism to address difficulties arising from specified conditions.