A company is sitting on forfeitures of about $65,000. Can they use that money as a retrospective credit for FSA administrative services rendered in the early 90's. For example, if they could produce invoices for FSA related admin going back to 1990 that add up to $65K could they take the forfeitures as a reimbursement for these expenses that were originally paid in full?

Those forfeitures, unless otherwise prescribed in the Section 125 plan document, become general assets of the company. They can use the money to throw a huge crawfish boil if they choose. Sometimes the document will state that forfeitures will be used to offset administrative expenses, or will be donated to charity, or will be used to buy Christmas turkeys for all employees, etc. Otherwise, re-roof the building, buy new office furniture, etc.