Not sure how unwieldy this would be (as I honestly don't know how prevalent mega backdoor Roths are) - but would it be helpful if we had a sticky post for knowing which large employers allow at least after-tax 401k contributions and possibly in-service distributions of these after-tax contributions?
I'm envisioning a table* of large companies (S&P 500 companies?), cities, large school districts, states, or any other large employer that have the mega backdoor Roth available to them. It seems like this is something difficult to research on the outside but if we had forum members with experience doing so all in one place, it might be helpful?
* Perhaps five columns: one for #, one for employer name, one for state or geographic area in which this is occurring, one for ability to put checkmarks (or x marks, whatever) on whether the employer allows after-tax 401k contributions, and the last one for ability to put checkmarks on whether the employer allows in-service distributions of these after-tax contributions. Possibly a 6th column to know the year in which it last happened just to try and keep up with policies.
Any follow-up post of someone with experience doing a mega backdoor Roth at a new company, city, school district, etc. would then be added to the table at the top.