If a taxpayer has taken a deduction to arrive at federal taxable income for the purpose of having that income taxed in a manner different from the taxation of federal taxable income, the amount which was deducted and specially taxed shall be added to federal taxable income in the computation of state taxable income. However, if any portion of the amount added was treated as capital gain in arriving at federal taxable income, that portion shall be treated as capital gain in the computation of state taxable income.
ORS 316.737