Without getting into too much detail, we can't tell you whether maybe you should try six years (if there is a foreign tax credit) or maybe even longer if there was an NOL in an open year that can be carried back.  It's generally a waste of time to go back more than three years, although some states allow four.  

Without getting into too much detail, do you think I should keep my used car that requires some maintenance, or buy a new one?