cost basis for Roth conversion when filing PA tax return
I had a Roth conversion from a traditional IRA to a Roth IRA in 2020 and 2021. In 2020, I converted most of the fund from the traditional IRA to the Roth IRA but left about $1000 in the traditional IRA. In 2021, I converted the entire amount in the traditional IRA to the Roth IRA. In both years, I contributed up to the limit using after tax money. Now, I am trying to file my PA tax return. I am not sure how to calculate the cost basis for the conversion in 2021. I know that I have $7000 contribution in 2021. That should be part of the cost basis. But, for the $1000 left in the traditional IRA, I do not know how to calculate the cost basis. If I do not count any of the contributions in 2020, would that mean I under-report the cost basis leading to paying higher tax. If I count the whole $1000 in the cost basis, it does not make any sense as part of the $1000 was from the growth in 2020. But, if the cost basis is something in between, how should I calculate it?