Calculating Week-To-Date values using DAX

The expression language of Tabular Mode SSAS - DAX - provides several great time intelligence functions. One of those it does not provide though a composite function - like DATESMTD or DATESQTD - is one to calculate Week-To-Date summations. To calculate this type of value, a custom expression using the DATESBETWEEN function is needed.

In this post, I'll show you what inputs are needed for the DATESBETWEEN function, how to create a custom start date using DAX, and how to implement this solution in your Tabular Model. Note that this solution will also work with PowerPivot for Excel, but the examples show will be using SQL Server Data Tools.