The after-tax amount rolled over from the 401(k) plan must be included on Form 8606 line 2 and an statement needs to be included with your tax return to explain this adjustment to your basis in nondeductible traditional IRA contributions.
In TurboTax, after entering the From 1099-R for the distribution from the traditional IRA and answering the immediate follow-up questions, click the Continue button on the Your 1099-R Entries page and proceed to where TurboTax asks if you made any nondeductible contributions to your traditional IRAs. Answer Yes, then click the EasyGuide button on the Let's Find You IRA Basis page. Proceed to where your can mark the box to indicate that you transferred money from an employer's plan to an IRA, click Continue, then enter the after-tax amount rolled over from the 401(k) and click Continue again. Finally, enter the explanation indicating that this adjustment is for after-tax money rolled over from the employer plan and continue through the rest of this section. TurboTax will place the after-tax amount on line 14 of the IRA Information Worksheet in TurboTax, to be included on Form 8606 line 2.
