What PREVIOUSMONTH does
Return dates from the previous month. In Power BI, the key is not only the formula itself but how it behaves with slicers, relationships, visuals and totals.
Syntax or pattern
PREVIOUSMONTH(dates)5 practical business examples
PREVIOUSMONTH in a sales report
Calculate sales from the start of the year to the current date.
Sales Previous Month = CALCULATE([Total Sales], PREVIOUSMONTH(Calendar[Date]))Requires a proper marked date table.
Sales last year
Shift the current period to last year.
Sales Previous Month = CALCULATE([Total Sales], PREVIOUSMONTH(Calendar[Date]))Use this for year-over-year comparisons.
Previous month sales
Compare current sales to the previous month.
Sales Previous Month = CALCULATE([Total Sales], PREVIOUSMONTH(Calendar[Date]))Useful for monthly trend cards.
Rolling 12 month sales
Calculate sales over the last 12 months.
Sales Previous Month = CALCULATE([Total Sales], PREVIOUSMONTH(Calendar[Date]))Good for smoothing seasonality.
Month-to-date target check
Compare current sales against current month target.
Sales Previous Month = CALCULATE([Total Sales], PREVIOUSMONTH(Calendar[Date]))Use with month filters for target reporting.
Common mistakes to avoid
- Using PREVIOUSMONTH before checking whether the data model has the right relationships and filter direction.
- Writing one complex measure instead of creating simple base measures first.
- Testing only at the total level and not checking row, category and date contexts.
- Forgetting that slicers, visuals and relationships can all change the filter context.
FAQ
When should I use PREVIOUSMONTH in DAX?
Use PREVIOUSMONTH when the calculation pattern matches the business question and the result behaves correctly in the current filter context.
Why is my PREVIOUSMONTH measure returning the wrong total?
Most total issues come from row context, filter context, relationships, or using a column aggregation where an iterator or CALCULATE pattern is needed.
Can I use this PREVIOUSMONTH pattern in a calculated column?
Some patterns work in calculated columns, but most reporting calculations should be measures so they respond to slicers and report filters.