A starting point would be to look at your Form W-2 and compare it with last year. Compare Box 15 through 17 on your W-2 with last year to see how that information is changed.
Box 17 will show the taxes withheld by your employer during the year so if less withholding was done this year compared to prior year then you will have to pay more when compared to last year.
Additionally, if you earned more income this year compared to last year, then you would have most likely moved in a higher tax bracket and hence you would have to pay more taxes this year.