File your Arts Tax return online. Pay your tax due with Visa, Mastercard, Discover Card, ACH payment, or mail a check or money order.Check out answers to your questions about Portland's unique tax forms. You can then easily file your Portland taxes with TaxAct. Withholding certificate. Pay at pro.portland. All payment and filings should be sent to the City of Portland through their Portland Revenue Online (PRO) system. All payment and filings should be sent to the City of Portland through their Portland Revenue Online (PRO) system. In Oregon, the highestprofile of those may be the bond ask for the Portland zoo. How to Change Party Enrollment: Simply fill out a new voter registration card and indicate your new preference.