We talk about Variable Compensation or Custom compensation when a company offers employees social benefits to one or more employees.
Company can offer insurances, restaurant or transport tickets and all kinds of social benefits to an employee and the cost is taken from their salary. For the employee this is really an improvement of their purchasing power, as the cost amount will be deducted from their gross salary. This way, the employee will pay less in taxes (IRPF, for example in Spain) at the end of the month.
In Spain, an employee can, legally, get up to a 30% of their salary as variable compensation. For the companies this is a very useful way to increase salaries without having to increase their expenses.