My 1099R shows Taxable amount not determined. How do I enter in TurboTax that $0 is taxable? (This was a roll over to another retirement account.) TurboTax did not ask.

If the rollover was from a traditional IRA to another traditional IRA then you will have these follow-up questions:

1. Login to your TurboTax Account 
2. Click on "Search" on the top right and type “1099-R”
3. Click on “Jump to 1099-R” and enter your 1099-R
4. Continue to "Tell us if you moved the money through a rollover or conversion" screen and select "I rolled over some or all of it to an IRA or other retirement account within the time limits (normally 60 days)"
5. Continue answering the questions.

If the rollover was from a 401k to a traditional IRA then you will have to answer these questions after you enter your 1099-R to indicate the rollover:

1. On the "Did you move this money from a 401(k) to a Roth 401(k)?" screen answer "No"
2. On the "Did you move the money to a Roth IRA?" screen answer "No"

Please be aware, if you moved pre-tax funds to a Roth IRA (Conversion) then this will be taxable.

You can check your entries on Form 1040 line 4 (IRA) or line 5 (401k).  If it was a rollover 4b/5b taxable amount should be $0 and ROLLOVER should be next to it.

To preview Form 1040:

1. Click on "Tax Tools" in the left menu
2. Click "Tools"
3. Click "View Tax Summary" in the Tool Center window
4. Click on "Preview my 1040" on the left