A commission is not always calculable by the regular pay day for the workweek in which it was earned — sales may not close out, or the commission plan itself may run on a monthly or quarterly cycle. In that situation, the employer may disregard the commission when computing the regular rate and, until the commission can be ascertained, pay overtime at not less than one and one-half times the employee's hourly rate exclusive of the commission. That is a placeholder, not a final answer: once the commission is computed and paid, the employer must also pay whatever additional overtime is due because the commission, once folded into the regular rate as covered in Chapter 1, changes that rate. The general method is to apportion the commission back over the workweeks of the period in which it was actually earned. Then, for every workweek in that period in which the employee worked over the applicable maximum hours standard (generally 40 hours per week), the employer pays additional overtime of not less than one-half of the resulting increase in the hourly rate, multiplied by the overtime hours worked in that week.

Sometimes apportioning the commission to the specific weeks that earned it is not possible or practicable. When that is the case, the employer must adopt some other reasonable and equitable method of allocation rather than skip the recomputation. Two such methods are recognized: assuming the commission was earned in equal amounts across each week of the computation period — the span of time over which the commission is earned and calculated, whether a month, a quarter, or whatever interval the employer's commission plan runs on — or assuming it was earned in equal amounts for each hour worked in the period. Which one fits depends on the facts — an equal-per-week assumption stops being reasonable if the employee's hours varied a great deal from week to week within the period.

A related problem is delayed credits and debits: a sale credited or a return debited after the fact can shift what a commission period's earnings actually were, even though the underlying work happened earlier. Rather than reopening the prior computation period, the employer may accept the amount actually paid to the employee for the current computation period as that period's total commission earnings. This is the commission amount as finally computed and disbursed for that period, already reflecting any sales credited or returns debited late, so the employer is not required to separately trace or recompute which earlier period those credits or debits actually arose in. The employer then allocates that amount over the span running from the last commission computation date to the present one. The hourly-rate increase and additional overtime are then computed the same way as for any other deferred commission.