I think the instructions for checking the 1040 at the end are wrong. The taxable amount should not be zero it should be equal to the amount converted from the reg IRA to the ROTH IRA.
The instructions under Step 1: Enter the Non-Deductible Contribution to a Traditional IRA
- Check the box for Traditional IRA and Continue
are wrong. You need to check the box "Roth IRA"
Then all the numbers work out.
4a: Ira Distributions: $150160
4b: Taxable amount: $150160
@https://ttlc.intuit.com/turbotax-support/en-us/help-article/retirement-benefits/enter-backdoor-roth-ira-conversion/L7gGPjKVY_US_en_US?uid=lfabjfq3
