A self-employed individual has a net earned income of $100,000 (after subtracting 1/2 SE tax)

Their DB contribution requirement is $90,000.

Can they defer $16,500 into the 401(k) plan, or are they limited to $10,000?

Assume no employer contribution to the DC plan.

$10,000 - because of the 415(c) limit. Also, makes no difference if there are catch-up deferrals because of 414(v)(2)(A). I believe this is poorly understood and when I last checked a few yrs ago some software vendors don't follow this and allow 401k deferrals when they should not, even in a DC only plan w/o the DB plan complication.

Their DEDUCTION is limited to $100k. So there would be no point in depositing a "salary deferral" of more than $10k.

.. Scott

Agreed - Thank you!

Scott, conceptually I think you are mistaken. It's not the deduction that is limited. 404n trumps 404a8C. It's the 415 limit that is relevant here.

Don't think so. 404(n) applies to paragraphs 3, 5, and 7 of 404(a). The limit of deductions for self-employed individuals is contained in 404(a)(8).

.. S

My bad. I had thought 404(n) completely overrode other sections.