If you have a lot of investments there is an extra Medicare tax on Schedule 4 line 62 which goes to 1040 line 14. That is offset with an extra amount on line 16 with withholding.
Or did you make a payment with extension or estimated payments that should be on line 17?
You might have to delete the W2s and re enter them. That usually clears something out. After you delete them see if you still have an amount on line 16 for withholding.
