26 CFR § 301.7503-1 - Time for performance of acts where last day falls on Saturday, Sunday, or legal holiday.
(a) In general. Section 7503 provides that when the last day prescribed under authority of any internal revenue law for the performance of any act falls on a Saturday, Sunday, or legal holiday, such act shall be considered performed timely if performed on the next succeeding day which is not a Saturday, Sunday, or legal holiday. For this purpose, any authorized extension of time shall be included in determining the last day for performance of any act. Section 7503 is applicable only in case an act is required under authority of any internal revenue law to be performed on or before a prescribed date or within a prescribed period. For example, if the 2-year period allowed by section 6532(a)(1) to bring a suit for refund of any internal revenue tax expires on Thursday, November 23, 1995 (Thanksgiving Day), the suit will be timely if filed on Friday, November 24, 1995, in the Court of Federal Claims, or in a district court. Section 7503 applies to acts to be performed by the taxpayer (such as, the filing of any return of, and the payment of, any income, estate, or gift tax; the filing of a petition with the Tax Court for redetermination of a deficiency, or for review of a decision rendered by such Court; the filing of a claim for credit or refund of any tax) and acts to be performed by the Commissioner, a district director, or the director of a regional service center (such as, the giving of any notice with respect to, or making any demand for the payment of, any tax; the assessment or collection of any tax).
(b) Legal holidays. For the purpose of section 7503, the term legal holiday includes the legal holidays in the District of Columbia as found in D.C. Code Ann. 28-2701. In the case of any return, statement, or other document required to be filed, or any other act required under the authority of the internal revenue laws to be performed, at an office of the Internal Revenue Service, or any other office or agency of the United States, located outside the District of Columbia but within an internal revenue district, the term legal holiday includes, in addition to the legal holidays in the District of Columbia, any statewide legal holiday of the state where the act is required to be performed. If the act is performed in accordance with law at an office of the Internal Revenue Service or any other office or agency of the United States located in a territory or possession of the United States, the term legal holiday includes, in addition to the legal holidays in the District of Columbia, any legal holiday that is recognized throughout the territory or possession in which the office is located.
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