last 30 days and hence a full year has 360 days. ISDA method If date A falls on the 31st of a month, then date A will be changed to the 30th. If date A falls on the 30th of the month after applying the rule above, and date B falls on the 31st of the month, then date B will be changed to the 30th. All months are considered to last 30 days except February which has its actual length. Any full year, however, always counts for 360 days. BMA/PSA method If date A falls on the 31st of a month or last day of February, then date A will be changed to the 30th. If date A falls on the 30th of the month after applying the rule above, and date B falls on the 31st of the month, then date B will be changed to the 30th. All months are considered to last 30 days and hence a full year has 360 days. Alternative European method (30E+/360) If date A falls on the 31st of a month, then date A will be changed to the 30th. If date B falls on the 31st of a month, then date B will be changed to the 1st of the following month. Where date B falls on the last day of February, the actual date B will be used. All months are considered to last 30 days and hence a full year has 360 days. See also 365-day calendar, another accounting calendar with fixed year length Day count convention, standards for counting days French Republican Calendar, a calendar with twelve 30-day months and five or six appended holidays Iranian calendars, where the Old Persian calendar had 360 days with an extra month added every 6 years References Specific calendars Bonds (finance) Settlement (finance)