EOMONTH is a function in Google Sheets that is typically used to return values for use in other functions rather than for using by itself. You are already going to know the ending day of most given months. However, if dates are changing in different parts of your spreadsheet, the last day of the month could be changing as well which would be quite difficult to nail down without this formula.
Remember when using the EOMONTH function that dates behave differently than numbers, and therefore you cannot type the date directly into the formula. You will need to use quotes, the DATE function, or a reference to a cell containing a valid date value.
Returns the end date of a month that is a specified number of months away from a starting date
start_date Any day during a starting month. 1/3/2017 and 1/6/2017 would both give the same output.
number_of_months Number of months to go forward or backward
Tip: The value for the number of months will be truncated instead of rounded if you use a decimal. For example, 3.7 will be changed to 3 instead of 4.
Example 1 - Plain and Simple
A few examples of the EOMONTH function. Notice that the values returned are the end of each month. If you want to increment by months and stay at the same day of the month, consider using the EDATE Function function.
|=EOMONTH("5/17/2017",13)||Return the last day of the month 13 months after May 17, 2017||6/30/2018|
|=EOMONTH("5/17/2017",-13)||Return the last day of the month 13 months before May 17, 2017||4/30/2016|
The examples show EOMONTH increasing and decreasing the month.
Example 2 - Calculating employment benefit start dates
Many times, benefits start after an employee is at a company for a certain number of calendar months. It does not matter when during a month the employee started, only how many whole months have elapsed. Below is a table that calculates the day after which the employee becomes eligible for benefits.
|1||Hire Date||Formula||Day after which eligibility starts|
Even though the three employees started within days of each other, one of them has a different eligibility date.
Live examples in Sheets
Go to this spreadsheet for the examples of the EOMONTH function shown above that you can study and use anywhere you would like.