<prompt> Human: My income is 70k per year while my wife makes around 18k per year. Does it make more sense to file jointly or separately, and why? Thanks in advance.  <response>: Using 2018 tax reform ... See Kats reply if you are talking about 2017.MFS: 70K pays 8700, 18K pays 600MFJ: 88K pays 7299---Why?MFS 70000 12000 58000 taxable. 9525 taxed at 10 952.50 29175 taxed at 12 3501.00 19300 taxed at 22 4246.00 953 3501 4246 8700MFS 18000 12000 6000 taxable. 6000 taxed at 10 600MFJ 88000 24000 64000 taxable. 19050 taxed at 10 1905 44950 taxed at 12 5394 1905 5394 7299Actual tax numbers may be slightly different by a few dollars because tax table uses ranges of income and assigns midpoints tax as the tax for the range.tldr: You save over 2000 dollars by filing jointly rather than separately.Caveat: If either of you has income based repayment of student loans, that might change the decision. 