[sfotm]

This is only true if your plan supports deferrals, right?

Had after-tax deferrals available through a Fidelity plan at an employer once, it was great being able to roll that over into an IRA. Hopefully I'll have it again soon - it's an underrated perk for sure.

[satvikpendem]

Correct, the employer and plan must support after-tax contributions, ie a mega backdoor Roth IRA. I posted more here: https://news.ycombinator.com/item?id=34279921