Why I just add $1251 more in income, then federal tax due increase $414 & WI tax due increase $117, so much? (but our total income is less than $50000 for me & my spouse)

[AnnetteB]

Your tax return is more complicated than just adding income and seeing how your balance due may change.  It depends on what type of income you added, whether it caused any additional taxes or penalties, how it affected any credits you are getting, whether there was any tax withheld to cover that income, and even whether it bumped you into a different tax bracket.  The same is true for your state return.  It all works together to determine your overall refund or balance due and you should not put a lot of faith into watching that number at the top of the screen change until you have entered everything.