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. Note: It is important to download and save the form to your computer, then open it in Adobe Reader to complete and print. After you download the waiver, please print it, fill it out and mail it to LWV of Portland, PO Box 3491, Portland OR 97208-3491. In Oregon, the highestprofile of those may be the bond ask for the Portland zoo.