1033.19. For the purposes of subparagraph b of the third paragraph of sections 1033.17 and 1033.18, a month means a period that begins on a particular day in a calendar month and that ends(a) on the day immediately before the day in the following calendar month that has the same calendar number as the particular day, or
(b) where the following calendar month does not have a day that has the same calendar number as the particular day, on the last day of the following month.