29 C.F.R. § 778.306

(a) The reductions in pay described in § 778.304(a)(4) are not, properly speaking, “deductions” at all. If an employee is compensated at a fixed salary for a fixed workweek and if this salary is reduced by the amount of the average hourly earnings for each hour lost by the employee in a short workweek, the employee is, for all practical purposes, employed at an hourly rate of pay. This hourly rate is the quotient of the fixed salary divided by the fixed number of hours it is intended to compensate. If an employee is hired at a fixed salary of $200 for a 40-hour week, his hourly rate is $5. When he works only 36 hours he is therefore entitled to $180. The employer makes a “deduction” of $20 from his salary to achieve this result. The regular hourly rate is not altered.

(b) When an employee is paid a fixed salary for a workweek of variable hours (or a guarantee of pay under the provisions of section 7(f) of the Act, as discussed in §§ 778.402 through 778.414), the understanding is that the salary or guarantee is due the employee in short workweeks as well as in longer ones and “deductions” of this type are not made. Therefore, in cases where the understanding of the parties is not clearly shown as to whether a fixed salary is intended to cover a fixed or a variable workweek the practice of making “deductions” from the salary for hours not worked in short weeks will be considered strong, if not conclusive, evidence that the salary covers a fixed workweek.