26 CAR § 100-103 – Date of performance — Arkansas Code § 26-18-105

(a) United States Postal Service postmark — Arkansas Code § 26-18-105(a)(2). Only the postmark of the United States Postal Service shall qualify for the provisions of this part for the filing of a return, claim, statement, or other documents beyond a prescribed due date.
(b) When last day is a Saturday, Sunday, or legal holiday — Arkansas Code § 26-18-105(b). When the last day prescribed under the authority of state tax laws for performing any act or instituting any suit falls on a Saturday, Sunday, or legal holiday, the performance of the act shall be considered timely if it is performed on the next succeeding business day that is not a:
1. (1) Saturday;
2. (2) Sunday; or
3. (3) Legal holiday.