The limit for total per-employer contributions in 2018 is $55,000. I have a 403b, a 457b, and a Defined Contribution plan through a single employer and I can make after-tax contributions to the DC plan. I'd like to do a mega backdoor roth via the DC plan's after-tax contributions.
If I contribute to the 403b, the 457b, and pre-tax to the DC plan, how much can I contribute after-tax to the DC plan? Do my contributions to the 403b and 457b count against the $55000 annual limit for this purpose?