Rebate U/s 87A & Penalty U/s 271f

Filing of return is mandatory if gross total income exceeds Rs 250000. It does not matter whether tax liability is there or nil and nothing to do with rebate. The provisions for filing of return and allowance of rebate are independent. Thus penalty in your case may be imposed. Also note that the government introduced the concept of rebate instead of increasing the basic exemption limit only to attract more filers and at the same time to give relief by way of rebate