Reduced hours for exempt employees: Should they continue to fill out time sheets?

Q. As a cost-saving measure, our company reduced the salaries of exempt employees by 10%. Employees get their salaries regardless of the number of hours they work. We have always asked our employees, though, to fill out a time sheet on which they write down 40 hours every week. Now we will ask them to record just 36 hours on this time sheet. Any problems with this?