Leap Years and Fiscal Periods

A company's fiscal year can end at any time, not just when a calendar year ends. When putting together a worksheet, you may want to calculate a date that is one year before or after a given date that represents the end of a fiscal period. This can be done quite easily with any number of formulas, such as the following:

=DATE(year(D1)-1,month(D1),day(D1))

This formula takes a date (cell D1) and subtracts a year from it. Thus, if D1 contains the date 6/30/07, then the formula returns 6/30/06.

This works great in most instances because most months have the same number of days from one year to the next. There is, of course, one exception--February. If you have a fiscal year that ends in February, the variable number of days in the month can play havoc with the above formula. If cell D1 contains 2/28/05, then the formula returns 2/28/04, when the real end of the fiscal period is 2/29/04. Similarly, if cell D1 contains 2/29/04, then the formula returns 3/1/03, which is obviously not what was intended.

There are a couple of ways you can determine the end of the fiscal period. The first is through the use of the EOMONTH function. This function is used to return the end of a month a given number of months in the past or future. For instance, if you wanted to know the last day of the month twelve months ago, you can use the following formula:

=EOMONTH(D1,-12)

The EOMONTH function is part of the Analysis ToolPak, so you will need to make sure you have it installed and enabled on your system. (How you do this has been covered in other ExcelTips.)

In some instances you might not want to use EOMONTH. For example, you might be distributing the workbook to others, and you are not sure if they have the Analysis ToolPak installed on their system. In such instances you could use the following formula:

=DATE(Year(D1)-1,Month(D1)+1,0)

This formula, just like the EOMONTH function, returns the end of the month for exactly one year ago. Another formula to return the end of month one year ago is as follows:

=D1-365-(DAY(D1)<>DAY(D1-365))