Employee's Withholding Allowance CertificateInternal Revenue Service: www.irs.gov
The purpose of this publication is to help you check your withholding and, if necessary, prepare a new Form W-4 to adjust your withholding. When you first start a new job, you must fill out a Form W-4 and give it to your employer to establish your initial withholding. You can adjust your withholding by giving a new Form W-4 to your employer at any time.IRS Withholding Calculator
If you are an employee, the Withholding Calculator can help you determine whether you need to give your employer a new 2018 Form W-4 Employee's Withholding Allowance Certificate to avoid having too much or too little Federal income tax withheld from your pay. You can use your results from the calculator to help fill out the form.