PBGC premium with a minimum benefit

[david rigby]

i have a conventional DB plan with a special minimum:

the benefit provided by a prior account under a money purchase plan, with earnings.

That is, the DB plan is a restatement of the money purchase plan. As you might expect, the conventional DB accrual is often less than the benefit from the account balance. By the way, the account balance is credited annually with actual earnings, no min. or max.

Question: what is the guaranteed benefit for PBGC premium purposes?