Plan has aggregate funding method normal cost (minimum funding) of $40,000.
412 full funding limit for 90% RPA and ERISA are less than zero.
404 Unfunded RPA is $60,000.
Client wants to and plans on funding $40,000.

So if client pays $40,000 then the quesion is:
Does the FSA show a year-end balance of zero (no FFC) or is there a credit balance of $40,000 equal to $40,000 FFC + $40,000 contribution - $40,000 AFD?

The FFC is not affected by the contribution made so your credit balance will be 40,000.

...plus interest if any portion of the contribution was made before the end of the plan year.