The Oregon Employer Withholding Allowance Certificate is a form issued by the Oregon Department of Revenue, which employers use to calculate the amount of Oregon income tax to be withheld from an employee's wages. It is usually filled out by the employee when they begin a new job. There are two versions of the Oregon Employer Withholding Allowance Certificate: Form OR-W-4 and Form OR-W-4P. Form OR-W-4 is used for employees who are paid wages subject to Oregon withholding, and Form OR-W-4P is used for pension and annuity recipients. Both forms require the employee to provide information about their filing status, the number of allowances they are claiming, and any additional income tax withholding that they want to have deducted from their wages. The employer then uses this information to determine the amount of Oregon income tax to withhold from the employee's wages.