Post-tax contributions

[Guest merlin15]

In a 401(k) retirement plan that allows post-tax (voluntary) contributions, do all ppost-tax contributions have to be a payroll deduction?

In other words, can John Doe cut a check from his personal checking account, mail it off to his HR Administrator, and ask that it be contributed to his individual 401(k) account.

[MWeddell]

Yes, this is permitted by law, because the elective deferral requirement that the contribution be made before the cash is available to the participant does not apply to after-tax contributions. However, most plan documents do not permit this lump sum contribution.