Oregon Revised Statutes State Legislative Department and Laws § 174.120

(1) The time within which an act is to be done, as provided in the civil and criminal procedure statutes, is computed by excluding the first day and including the last day, unless the last day falls upon any legal holiday or on Saturday, in which case the last day is also excluded.

(2) For the purposes of determining whether a person has complied with a statutory time limitation governing an act to be performed in a circuit court, the Oregon Tax Court, the Court of Appeals or the Supreme Court, the time prescribed by law for the performance of the act does not include the day on which the specified period begins to run. The designated period does include the last day unless the last day is:

(3) If the last day of a designated period is excluded under the provisions of subsection (2) of this section, the act must be performed on the next day that the court is open for the purpose of filing pleadings and other documents.

(4) The provisions of subsections (2) and (3) of this section apply to time limitations established by statutes of limitation and other procedural statutes governing civil and criminal proceedings.

(5) If a statute of limitation or other procedural statute governing civil or criminal proceedings provides that an act be done within one or more years, the time for performing the act is computed in calendar years. If the specified period begins to run on a date other than February 29, the act must be done on or before the same date in the calendar year in which the specified period ends as the date in the calendar year in which the specified period began to run. If the specified period of time begins to run on February 29, the act must be done on or before February 28 of the calendar year in which the specified period ends.