$500 of tax is probably incorrect. If the $1,400 distribution was only a small portion of your Roth IRA balance, it's likely that none of the $1,400 distribution is taxable.
The amount of original contributions that you made to your Roth 401(k) (shown in box 5 of the Form 1099-R reporting the rollover from the Roth 401(k)) became contribution basis in your Roth IRA as a result of the rollover. When you click the Continue button on the Your 1099-R Entries page and proceed through the general follow-up questions, be sure that TurboTax shows the amount of basis rolled over from the Roth 401(k) included in the amount of your Roth IRA contribution basis.
