My 1099R says unknown in block 2a Taxable amount. What do I do bout that? Leaving the block empty causes the system to read the income as untaxable. I don't know if true

[ChrisJ]

If box 2a shows 'unknown' - leave it blank. 

The taxable amount is largely determined by Box 7 codes, but your distribution could still be taxable or subject to penalty. TurboTax uses the other info on your 1099-R, as well as your answers to the interview questions, to determine this.