I'm required to fill out a form 8606 because of a 401K rollover that contains after tax contributions. Where can I fill this in on turbotax

[dmertz]

Normally you would do this when you are next required to file Form 8606 for a new nondeductible contribution to your traditional IRAs or you make a distribution from your traditional IRAs.  The IRS generally does not want to receive a Form 8606 only to report the addition of basis received by your IRAs from a qualified retirement plan.

In TurboTax, to enter this basis the next time you are required to file Form 8606, go through the Deductions & Credits -> Retirement and Investments -> Traditional and Roth IRA Contributions section and indicate that you made nondeductible contributions to your traditional IRAs, then click the EasyGuide button on the Let's Find Your IRA Basis page.  TurboTax will give you the opportunity to indicate that you transferred money from an employer's retirement plan in 2015 or a previous year, then allow you to enter the amount and provide an explanation.