Division of Labor and Industry
The Maryland Guide to Wage Payment and Employment Standards -
Overtime - Salaried Employees: No Overtime
Salaried employees, who fit the description of "Executive", "Administrative" or "Professional", are generally exempt under the law from receiving overtime, regardless of the number of hours they are required to work in a week. Some employers, in attempting to avoid paying overtime, make the decision to pay a salary to workers who do not fit the definition of Executive, Administrative or Professional. This practice does not eliminate the obligation of an employer to pay overtime based on a mathematical calculation of the employee's average hourly wage to employees who are otherwise eligible.
For Executive, Administrative and Professional employees receiving salaries, an employer may not generally deduct or "dock" from wages any amount of time for missed work which is less than a full day. Doing so may remove the employee from the "exempt" status under the Wage and Hour Law, and entitle him or her to overtime pay after 40 hours. An employer may, however, deduct any of the hours of missed work from an employee's accrued leave reserves (e.g., vacation, sick leave, compensatory time, etc.) without jeopardizing the exempt status.
I found this but it doesn't say if it applies to all businesses/companies