Payables / Procurement / Receivables Forms ACH Enrollment Form (PDF 4.38 MB)(For Suppliers)W-9 Blank Fillable Form (PDF 267.75 KB)(For Suppliers)W-9 Supplier Letter (PDF 2.09 MB)(For Suppliers)W-9 for Washington County (PDF 58.21 KB)(For Customers)Washington County IRS Tax Exemption Letter (PDF 49.02 KB)Washington County Oregon Business Registry Resale Certificate (PDF 34.88 KB) LocationFinance155 N First Avenue Hillsboro, Oregon 97124 Hours and directions