We cannot answer that since we do not know if you told the state to withhold tax from your unemployment. What did you select when you signed up for unemployment? You have to tell them whether you want tax withheld when you enroll. You will get a 1099G for the unemployment and it will show any tax that was withheld. If you receive the "back pay" unemployment in 2021 it will go on your 2021 tax return.