Roth Conversion 1099-R

Hi, I have a 1099-R that has $20,000 from a conversion I did from a traditional IRA to a Roth IRA and the codes shown are 2K. I thought this would be taxable, but when entering the information from all boxes into TurboTax it says that I don't owe any taxes on that amount that was converted. On my 1040 it shows $20,000 in box 4a, but then $0 in 4b and notes "ROLLOVER". Is this correct?