<prompt> Human: I am doing my taxes right now and have always claimed zero. Last year I got married and we filed jointly and we got a return of around 1,200. This year we are filing jointly again and we bought a condo as well and we are getting the benefit of deducting interest. I would think with all else equal our return would be higher, but now I owe about 4,500 and am getting penalized for not withholding enough throughout the year. Ill add that I started a new job in march, is it possible my employer messed up my withholdings and that is why I owe so much? How can I check that their withholdings are accurate? I am so stressed right now, appreciate any help.  <response>: we bought a condo as well and we are getting the benefit of deducting interest. It is possible that you dont get a benefit from it. What is the total value of your itemized deductions? If it is less than 12,600 the standard deduction for a married couple filing jointly, then you would not benefit from itemization. Any tax software program should automatically apply the highest deduction itemized or standard, but if you are doing it by hand it is possible to use the lower one. is it possible my employer messed up my withholdings and that is why I owe so much?It is possible that either you or your employer messed up. Many people also falsely assume they are supposed to check Married on their W-4 if they are married. However, that designation is intended for couples where only one partner works, or at least makes the majority of the wages. If you and your partner work, then you need to select Married, but withhold at higher Single rate. My guess is that you chose the wrong one. 