IRS Form W-4, Employee's Withholding Allowance Certificate, is available for download on the IRS website in the universal portable data format, commonly referred to as PDF. Form W-4 is used by employers to withhold federal taxes from employee wages.
To standardize the withholding of taxes from employee wages, the IRS provides Form W-4. An employee completes the worksheet and submits it to his employer. The form summarizes the employee's federal tax filing status, number of dependents and potential deductions, and ensures the appropriate amount of tax is withheld throughout the year. The IRS recommends updating withholding certificates whenever an employee's personal or financial situation changes significantly. Specifically, marriage, divorce or the birth of a child can change the number of allowances claimed, as can a spouse beginning or ending a job.
Withholding too little tax can result in federal taxes being due and, in some cases, penalties owed for late payment of tax. Withholding too much tax can result in a federal tax refund, but unnecessarily reduces take-home pay during the course of the tax year. By correctly calculating the taxes likely to be owed to the federal government, a taxpayer can avoid either incurring preventable penalties or effectively making an interest-free loan to the government to be refunded later.