(a) Whenever periods of time are specified in this part in days, calendar days are intended. When the day, or the last day fixed by statute or by or under this part for taking any action or paying any fee in the United States Patent and Trademark Office falls on Saturday, Sunday, or on a Federal holiday within the District of Columbia, the action may be taken, or the fee paid, on the next succeeding business day which is not a Saturday, Sunday, or a Federal holiday. See § 90.3 of this chapter for time for appeal or for commencing civil action.

(b) If the day that is twelve months after the filing date of a provisional application under 35 U.S.C. 111(b) and § 1.53(c) falls on Saturday, Sunday, or on a Federal holiday within the District of Columbia, the period of pendency shall be extended to the next succeeding secular or business day which is not a Saturday, Sunday, or a Federal holiday.

[65 FR 14871, Mar. 20, 2000, as amended at 78 FR 62395, Oct. 21, 2013]