Here is a useful tip for finding the month-end from a transaction date.

I often have a need to identify the month-end date relating to a particular transaction during the month, i.e. we have the date of the transaction and need to return the date of the month-end.

NB: Most businesses in my experience tend to use calendar months for accounting periods these days, however some (particularly in manufacturing) still have month-ends on a particular day of the week. My tip below will only work for calendar months, but I may cover irregular month-ends in a future post (hint, you will need VLOOKUP).

Another NB: It has been pointed out to me by a number of readers that there is a quicker solution than that outlined below for users of Excel 2010. It uses a function which I didn’t know was there as I didn’t need it, having an approach that served me well in earlier versions. In Excel 2010, you can use =EOMONTH(A1,0), where A1 contains the transaction date. The method below is still worth knowing as you will need it if a file has to be accessed by earlier Excel versions. It also uses a number of techniques for manipulating dates that you can use for other purposes.

Here we can use an interesting and very useful feature of the DATE function, along with the YEAR and MONTH functions.

The DATE function returns a date given the year month and day, and is entered as follows:

=DATE(year,month,day)

so =DATE(2012,7,16) returns 16th July 2012 (in whatever date format you have set for the cell).

The YEAR, MONTH and DAY functions work the other way, in that they pull out the year, month and day numbers respectively from a date, so if cell A1 contains the date 16th July 2012, =YEAR(A1) will return 2012.

We could use this to pull out a particular day of the month from any transaction, so if we wanted to return the 25th day of the month of the transaction (where the transaction date,16th July 2012, is held in cell A1), we could use:

=DATE(YEAR(A1),MONTH(A1),25)

which would return 25th July 2012.

However, the actual month-end day obviously varies between the 28th and the 31st. This is where the useful quirk of the DATE formula comes in. Day zero of the month is the last day of the previous month, so

DATE(2012,8,0) returns 31st July 2012.

We can therefore amend the DATE formula above to provide the month end for the transaction date in A1,  to provide: