If the date for a return falls on a Saturday, Sunday, or legal holiday, the due date
                  is the next succeeding day which is not a Saturday, Sunday, or legal holiday. The
                  return is treated as timely filed for IRS purposes if it is mailed by the due date;
                  thus, a return due on April 15 is treated as timely filed for IRS purposes if mailed
                  on April 15.