Using TurboTax online premier for deceased mother's 2020 tax return - died 1/4/21. Where do I enter the April $1200 stimulus payment in the income section?

The stimulus payment is not taxable, but it does need to be entered in the program to determine if you are due any additional stimulus payments. When you get towards the end of the program in TurboTax, after you have entered your income and deductions, you will be asked how much you received in stimulus payments.