Final answer:
The IRS provides tables for withholding federal and local income taxes from employees' paychecks. Group insurance and net pay are not covered by IRS tables. Payroll taxes, including social security and Medicare, comprise a significant part of federal revenue.
Step-by-step explanation:
The Internal Revenue Service (IRS) provides employers with tables that indicate the amounts to withhold from employees' paychecks for specific purposes. Among these are federal income tax withholding, which is a significant portion of federal government revenue and is typically due every year by April 15th.
The IRS does not provide tables for group insurance or net pay as those are determined by the employer or the specific insurance plan. Local income taxes, where they exist, are also withheld and are typically guided by state or local tables.
Taxes such as social security and Medicare are included in payroll taxes and represent major components of federal revenue, accounting for over 80% of it. The withholding system is a form of pay-as-you-go tax, whereby the amounts are withheld throughout the year, making it efficient and reducing the burden during tax filing season.