((service performed/(service required) x annual salary) - salary received =
salary due
where the service performed and service required are in terms of quarters, trimesters, months, weeks, or other appropriate units consistent with the obligation requirements at the campus concerned, and the salary received is that amount actually paid to him for the period indicated in the formula as service performed.
N.Y. Comp. Codes R. & Regs. Tit. 8 § 308.3