Where a salesperson is not paid commission until the pay date in the month after the one in which she earned it, is the employer obliged to pay her commission earned before she went on maternity leave, while she is on maternity leave?

Yes, an employee is entitled to be paid any sum earned before the start of her maternity leave regardless of whether it is actually paid after her leave has started. She should be paid it in the usual manner and on the day it is due, in this case on the pay day in the month after the one in which it was earned.

During ordinary and additional maternity leave an employee is entitled to her contractual terms and conditions apart from "remuneration", ie normal salary or wages. Most employees who meet the qualifying conditions receive statutory maternity pay (SMP) instead of their normal salary. However, where an employee is owed pay, including commission, bonuses or performance-related pay, in relation to the period during which she worked, she can be paid it during her maternity leave, without her SMP being affected.