For post-tax dollars to a 401K am I supposed to include on form 8606 for Nondeductible IRAs?

[Vicki1]

I contributed post-tax dollars to a 401K (in addition to the 18,000 pre-tax 401K contribution limit).  Am I supposed to include these post-tax 401K contributions on form 8606 for Nondeductible IRAs?

[macuser_22 · Accepted solution]

A 401(k) is not an IRA and does not get reported on a 8606.

You do not report after-tax 401(k) contributions anywhere on a tax return, until you take a distribution.   The employers plan trustee must track pre-tax and after-tax contributions.