I will go from 3 Federal tax exemptions to 2 for tax year 2016, and my W-4 withholding is already at M-0. Does it make more sense from a tax perspective to either A) put the full amount of over age 50 catch-up contributions into my TSP ($6000) to reduce my taxable income or B) change my W-4 to have additional money withheld from my pay?
