Are you entering her 1099G in the right place? Maybe you picked the wrong kind of 1099G. If you are in the right place for a 1099G for unemployment there are boxes for the tax withheld.
UNEMPLOYMENT COMPENSATION
Unemployment compensation is taxable on your federal return.
You will have to enter a 1099G that is issued by your state.
Some states will mail out the 1099G. Or you might need to go to your state’s unemployment website and use the password, etc. that you have been using to certify for weekly benefits to get your 1099G from the state’s site.
Enter your 1099G in Federal>Wages & Income>Unemployment
Go through the screens very carefully, making sure to enter any federal/state tax you had withheld from the unemployment.
The boxes to enter the withholding will come up if you check the box indicating that there was withholding from unemployment.
Are you doing a 2020 return? Are you using the Desktop program installed your computer? Online is only good for 2021 now.
To enter withholding on Unemployment:
After you enter the Payer's name & address then on the next screen you select your state and enter the amount of Unemployment, there is a checkbox that says "Federal or state income tax was withheld on this payment". You have to check it for the withholding boxes to show up on the next screen.
For 2020 the federal income taxes withheld from the Form 1099-G will be included on the federal tax return, Form 1040 Line 25b.
Turbo Tax expert answer with screen shots of both Online and Desktop programs to enter withholding on unemployment