Oregon Revised Statutes Revenue and Taxation § 314.855

The Department of Revenue may pay rewards to persons, other than officers or employees of the department, furnishing information that leads to the recovery of tax from other persons guilty of violating the provisions of income tax laws. Such rewards shall not exceed 10 percent of the net amount of tax, penalty and interest recovered by suit or otherwise and shall be paid only in cases where such evasions of tax would not be disclosed by the audit of returns or from other information available to the department.