Finance Minister P Chidambaram has indicated that the government may tinker with the excise duties and service tax rates in the interim budget in an apparent bid to boost economy. He, however, said that the government cannot propose amendments to the Income Tax Act, Customs Act or the Excise Act. But any proposal short of amending a law can be made. Mr Chidambaram was addressing a press conference on the eve of Parliament session in New Delhi yesterday. He said, his vote-on-account budget to be presented in the Lok Sabha on February 17 will be short and he will prefer a debate on that.