What do I do with the rollover Roth IRA if I haven't maxed out my pre-tax 401k?

[unicorn1988]

I converted $800 after-tax 401k to Roth IRA (Mega Backdoor) last year, but just realized I didn't max out pre-tax 401k. The $800 is already on my 1099R form. I heard the mega backdoor won't work if pre-tax 401k isn't maxed out, but I'm not sure what tax problem there will be. Is the rollover legit? Should I withdraw the $800 from my Roth IRA?

Thanks a lot for the help. 

[macuser_22]

As long as your 401(k) play allows rollover of after-tax money to an IRA it makes no difference.    Your 1099-R should have your contributions in box 5 and box 2a should be the box 1 amount minus box 5 which would be zero of all after-tax money.

[unicorn1988]

Thanks. Do I check with my employer to see if 401k plan allows the rollover?

[macuser_22]

The plan administrator.

But you said you did the conversion last year so they must allow it.   You should have a 1099-R for the distribution and it should show the after-tax amount as I said.

[unicorn1988]

Yep, thank you!