Thank you so much @FangxiaL
Yes, I also made $6000 contribution to the traditional IRA for 2021. So I made $12,100 Roth-IRA conversion in 2021 ($6000 from 2020 and $6000 from 2021 plus $100 taxable earnings).
I will follow your guidance and put $6000 as my IRA basis even though I don't have 2020 form 8606 at this point (going to file it soon).
One follow-up question, the address on my 2020 tax return is different from my current address, so for the 2020 form 8606 that I am going to file, what address should I use?
