how to calculate 2023 tax liability for 2210 purposes

compute what each of your separate tax liabilities would have been for 2023 using your 2024 filing status

then the 2023 joint tax liability times your share of separately computed tax liability divided by you combined separately computed tax liabilities is your share.  for this purpose the separately computed tax above can't be less than 0. 

if you used the standard deduction for 2023 both must use it in the separate computations. if you itemized then use your separate itemized deductions. This would require if using 2023 Turbotax to compute the liabilities, the box must itemize should be checked