Payroll taxes are taxes imposed on employers or employees, and are usually calculated as a percentage of the salaries that employers pay their staff. Payroll taxes generally fall into two categories: deductions from an employee’s wages, and taxes paid by the employer based on the employee’s wages. The first kind are taxes that employers are required to withhold from employees’ wages, also known as withholding tax, pay-as-you-earn tax (PAYE), or pay-as-you-go tax (PAYG) and often covering advance payment of income tax, social security contributions, and various insurances (e.g., unemployment and disability). The second kind is a tax that is paid from the employer’s own funds and that is directly related to employing a worker. These can consist of fixed charges or be proportionally linked to an employee’s pay. The charges paid by the employer usually cover the employer’s funding of the social security system, medicare, and other insurance programs. The economic burden of the payroll tax falls almost entirely on the worker, regardless of whether the tax is remitted by the employer or the employee, as the employers’ share of payroll taxes is passed on to employees in the form of lower wages than would otherwise be paid. 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.