In countries in which the average age of the population is increasing, tax advantages may put pressure on pension plans. For example, where benefits are funded on a pay-as-you-go basis, the benefits paid to those receiving a pension come directly from the contributions (money paid) of those of working age. If the proportion of pensioners to working-age people rises, the contributions needed from working people will also rise proportionately. In the United States, the rapid onset of Baby Boomer retirement is currently causing such a problem.