You can claim net itemized deductions or Oregon's standard deduction, whichever is larger, but not both.
If you are married filing separately and one spouse itemizes, both spouses must itemize deductions. If your spouse itemizes, your standard deduction is 0.
You can claim your total itemized deductions after federal limitations. You can claim itemized deductions for Oregon even if you do not have enough deductions to itemize on your federal return.
If you itemize for Oregon only, fill out a federal Schedule A for Oregon purposes. Be sure to include your state taxes even when itemizing for Oregon only, then subtract your Oregon state income tax. Use your federal adjusted gross income to figure the Schedule A limitations.
For more information, refer to Form 40 Instructions.