@jesslh15 wrote:
For tax year 2021, my husband and I filed Married filing Separately . . .
how do determine the AGI when we file jointly? Do we add our individual AGI from tax year 2021?
Do you mean the 2021 AGI that you have to enter in order to e-file your 2022 tax return? When you e-file a joint return, you have to enter the previous-year AGI separately for each spouse. (This is true no matter what your filing status was for the previous year.) So for your husband you will enter the AGI from his 2021 separate return, and for yourself you will enter the AGI from your 2021 separate return. You do not add them together.
@jesslh15 wrote:
Are they any penalties?
There is no penalty for changing your filing status.
