I have a one-man DB plan - participant has been receiving a LA annuity for the last 10+ years. If plan were to terminate today, there would a reversion of assets to the corporation after his payout or purchasing an annuity.

If he were to die while plan is still in existence, since benefits would obviously cease, do all remaining assets become a reversion to the corporation?

Is he receiving the 415 benefit? If not, amend the plan to increase the benefit, before purchasing the annuity.

I'm asking if annuitant receiving LA annuity from the plan should suddenly die, do all remaining assets in the plan become a reversion to the corporation?

If depends. If the plan purchases an annuity, probably not.

It must be late in the day - or year - please tell me, what is an "LA annuity"?

I suspect it means "life annuity" annuity - but repetition is a problem that just keeps coming back.

Lazy A** Annuity?

Nah.

Maybe from the department of redundancy department?

Yeah, that's it.