(18)Month means calendar month. In calculating a period expressed in terms of months and days, complete calendar months, irrespective of the number of days in each, should first be calculated and the odd number of days calculated subsequently.Audit instruction regarding Rule 9(18)In calculating a period of 3 months and 20 days from January 25, 3 months should be taken as ending on April 24, and the 20 days on May 14. In the same way the period from January 30 to March 2, should be reckoned as 1 month and 2 days because one month from January 30, ends on February 28.A period of one month and 29 days commencing from the 1st January will expire, in an ordinary year (in which February is a month of 28 days) on the last day of February, because a period of 29 days cannot obviously mean to exceed a period of full calendar month and leave for two months from 1st January would end on the last day of February. The same would be the case if February were a month of 29 days or if the broken period were 28 days (in an ordinary year).
