Pay an exempt employee less than the minimum weekly salary.
You must pay an exempt employee a salary of at least $455 a week to satisfy the administrative, executive or professional exemptions. There are several other tests with different compensation levels (i.e. the computer professional exemption or the highly compensated employee exemption).
Make deductions to an exempt employee's salary for the quantity or quality of their work.
Exempt employees must be paid their full salary for any work week in which they work. Employers may not make deductions for the quantity or quality of work.
Dock an exempt employee's salary for partial day absences.
There are several exceptions to the "no pay-docking" rule: (1) absences from work for one or more full days for personal reasons, other than sickness or disability; (2) absence from work for one or more full days due to sickness or disability if deductions made under a bona fide plan; (3) to offset amounts paid for jury duty, witness fees or military pay; (4) penalties imposed in good faith for violating safety rules of major significance; (5) unpaid disciplinary suspension of one or more full days imposed in good faith for violations of workplace conduct rules; (6) unpaid leave taken pursuant to the FMLA; (7) proportionate time paid in first and last weeks of employment.
Change the employee's job duties so they no longer meet the duties part of the test.
Each of the FLSA overtime exemptions (administrative, professional, executive) has a "duties" portion of the test for exempt status. For example, one element of the test for the executive exemption is someone "who customarily and regularly directs the work of two or more other employees." Don't make the mistake of assigning this manager to a one-person department!
Just pay everyone a salary and don't worry about job duties.
This one is not really how to lose an exemption, but rather how not to even qualify for one in the first place. Many employers believe (mistakenly) that you only have to pay an employee on a salary basis to avoid paying overtime. That is incorrect. The person definitely must be paid on a salary basis, but also must meet the "duties" test for the particular exemption. This is an area where an experienced HR professional or employment attorney can assist the employer.