Temporary lay-offs are used by companies to reduce costs at times when business is slack. A good example are the car factories, which reduce their production to cut costs and to anticipate on low sales.
Employees are told to stay at home for one or more days each week, or for a whole period. This avoids real lay-offs, and it's a cheap way for the companies to reduce costs.
Temporary unemployed receive an allowance from the Federal Labour Service RVA. Because of the rocketing number of temporary unemployed, this will cost the Belgian state an estimated 1 billion euros this year.