That worksheet is only used for special circumstances when there is a * (asterisk ) on line 15 on the 8606 form. The form is not intended to be filled out manually. If you enter the 1099-R in the interview it will ask for your non-deductible contribution and the 2019 year end value of all Traditional IRA accounts and automatically fill out the 8606 and worksheet if required.
A 2019 contribution made in 2020 will not offset any 2019 conversions and that goes on the 8606 line 4 and is subtracted from the amount of non-deductible basis for the tax calcification. Being able to contribute to 2019 in 2020 does not make the non-deductible basis retroactive to 2019 - it is not. The contribution made in 2020 for 2019 will only offset distributions made in 2020 or later years.
**Disclaimer: This post is for discussion purposes only and is NOT tax advice. The author takes no responsibility for the accuracy of any information in this post.**
