Did you enter all your tax forms and information? TurboTax will recalculate the amount due (or refund) every time you enter new information.There are many reasons why you might owe $451, such as: Your Income increased. You had a second job. You did not have enough taxes withheld during the year. You changed your Filing Status. Number of dependents claimed this year.I recommend that you make a line by line comparison between last year and this year's return to see what have changed.