All audits performed by or at the direction of the department of treasury for the purpose of determining liability for a corporate franchise fee levied pursuant to former Act No. 85 of the Public Acts of 1921, and all payments received and refunds made on the basis of those audits before the repeal of former Act No. 85 of the Public Acts of 1921 are declared to be valid and to have been in fulfillment of the legislative purpose to provide for fair administration and enforcement of that act.