This table is used to determine whether petitions are filed within 90 days after the notice of deficiency is mailed. All the dates in the year are arrayed in columns. Find the date of mailing and read across to the right, skipping one column. (If February 29 falls within the ninety days, subtract one day from the ending date found in the table.) Do not count Saturday, Sunday, or a legal holiday in the District of Columbia as the last day.