It is unlikely you will actual lower your taxes by filing MFS. The tax brackets are less favorable and some deductions and credits are reduced or disallowed. You can certainly test it out both ways. (For a few years, my wife and I filed MFS, which cost us an extra $500 in federal taxes but saved $1000 in state taxes, because the state and federal deductions and brackets were so different.). Remember that if one spouse uses itemized deductions, both spouses must itemize, even if they have nothing to deduct. It is not allowed to load all the deductions on one spouse so the other spouse can take the standard deduction.
