There are a few things you can do to double check your results:

Try a line by line comparison of your 2017 and 2016 returns-something may jump out at you and prompt you to adjust your 2017 return.

To view your 2017 Federal form 1040
1) Lower left side of the screen, click last category "Tax Tools"  (click the dropdown arrow).

2) Select "Tools"

3) Select "View Tax Summary" under “Other Helpful Links”

4) Then back to the left-side of the screen, click "Preview 1040"

If a line by line comparison does not reveal the difference, you should revisit all of your entries for accuracy and completeness starting with your W-2(s). Look for misplaced decimals or extra zeros.

Once you are satisfied that you have prepared an accurate return, consider a contribution to a deductible, Traditional IRA if you have not already done so.