38 CFR § 3.110 - Computation of time limit.
(a) In computing the time limit for any action required of a claimant or beneficiary, including the filing of claims or evidence requested by VA, the first day of the specified period will be excluded and the last day included. This rule is applicable in cases in which the time limit expires on a workday. Where the time limit would expire on a Saturday, Sunday, or holiday, the next succeeding workday will be included in the computation.
(b) The first day of the specified period referred to in paragraph (a) of this section shall be the date of mailing of notification to the claimant or beneficiary of the action required and the time limit therefor. The date of the letter of notification shall be considered the date of mailing for purposes of computing time limits. As to appeals, see §§ 19.52, 20.203, and 20.110 of this chapter.