Oregon Revised Statutes Counties and County Officers § 202.200

(1) If the new county is formed from one county, the new county shall pay its pro rata share of the amount of state taxes which the county from which it is formed is to pay for that year, and for each succeeding year thereafter until otherwise provided for, based upon the ratio that the taxable valuation of the property in the new county bears to the taxable valuation of the property of the original county before the new county was formed.

(2) If the new county is formed from more than one county, the new county shall pay its pro rata share of the amount of state taxes which each of the counties from which it is formed is to pay for that year, and for each succeeding year thereafter until otherwise provided for, based upon the ratio that the taxable valuation of the property in the area taken from each original county bears to the taxable valuation of the property in each original county before the new county was formed.

(3) In the event the election was for the purpose of a change in county boundaries and a portion of the territory in one county has been added to another county, the state taxes shall be adjusted in the same manner and upon the same basis as in the formation of new counties from more than one county.