Payroll taxes are taxes imposed on employers or employees, and are usually calculated as a percentage of the salaries that employers pay their employees. By law, some payroll taxes are the responsibility of the employee and others fall on the employer, but almost all economists agree that the true economic incidence of a payroll tax is unaffected by this distinction, and falls largely or entirely on workers in the form of lower wages. Because payroll taxes fall exclusively on wages and not on returns to financial or physical investments, payroll taxes may contribute to underinvestment in human capital, such as higher education.

Social insurance is a form of social welfare that provides insurance against economic risks. The insurance may be provided publicly or through the subsidizing of private insurance. In contrast to other forms of social assistance, individuals' claims are partly dependent on their contributions, which can be considered insurance premiums to create a common fund out of which the individuals are then paid benefits in the future.