# PREVIOUSMONTH

## Y ## What is the PREVIOUSMONTH function?

The PREVIOUSMONTH function in DAX is used to calculate the value of a measure for the previous month. It takes one argument, which is a date column or an expression that evaluates to a date or time value. The function then returns the value of the measure for the month that precedes the month specified in the argument.

## How to use the PREVIOUSMONTH function in Power BI

To use the PREVIOUSMONTH function in Power BI, you first need to create a measure that you want to calculate for the previous month. This could be a sales total, a revenue figure, or any other metric that you want to analyze.

Once you have created the measure, you can use the PREVIOUSMONTH function to calculate its value for the previous month. To do this, you need to create a new measure that uses the PREVIOUSMONTH function in its calculation.

Here’s an example of how to create a measure that calculates the sales total for the previous month:

``` Sales Previous Month = CALCULATE(SUM(Sales[Amount]), PREVIOUSMONTH('Date'[Date])) ```

In this example, we are using the CALCULATE function to calculate the sum of the sales amount for the previous month. We are passing two arguments to the CALCULATE function – the first argument is the expression we want to calculate (SUM(Sales[Amount])), and the second argument is the filter we want to apply (PREVIOUSMONTH(‘Date'[Date])).

The filter argument specifies that we want to calculate the sales total for the previous month, based on the date column in our data model. The PREVIOUSMONTH function is used to get the date for the previous month, which is then used to filter the data.

## Tips for using the PREVIOUSMONTH function

Here are some tips for using the PREVIOUSMONTH function in Power BI:

– The PREVIOUSMONTH function only works with a date column or an expression that evaluates to a date or time value. If you try to use the function with a non-date column, you will get an error.

– When using the PREVIOUSMONTH function, make sure that your data model includes a date table with a column that contains the dates you want to analyze. This is because the function needs to be able to find the dates for the previous month.

– You can use the PREVIOUSMONTH function in combination with other DAX functions, such as the TOTALYTD function or the SAMEPERIODLASTYEAR function, to create more complex calculations.

– Be careful when using the PREVIOUSMONTH function with data that is not regularly spaced (e.g. monthly data that skips a month). In such cases, the function may not return the expected results.

The PREVIOUSMONTH function in DAX is a powerful tool for analyzing data in Power BI. By allowing you to calculate the value of a measure for the previous month, it enables you to gain insights into trends and patterns that can help you make better decisions. By following the tips outlined in this article, you should be able to use the PREVIOUSMONTH function effectively in your Power BI projects.

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