title: DATEADD and missing dates
body: <p>How do you reliably add 10 months to a date in the DAX formula for a PowerPivot calculated column?</p>
  
  <p>My first attempt only works for dates that already exist in the EventDate column. </p>
  
  <pre><code>=DATEADD(Dates[EventDate], 10, month)
  </code></pre>
  
  <p>As Chris Webb wrote in his blog <a href="http://cwebbbi.wordpress.com/2012/01/06/the-dax-dateadd-function-and-missing-dates/" rel="nofollow">DATEADD is unreliable</a> as it returns blanks whenever the resulting date is not found in the EventDate column.</p>
  
  <p>My second attempt always returns data, but the day of the month is incorrect.</p>
  
  <pre><code>=[EventDate] + 10 * 31
  </code></pre>
  
  <p>Notes: All dates in EventDate are on the first day of the month. I am using PowerPivot for Excel 2010. The formula is for the financial year hierarchy in a date dimension.</p>
  
  <p>Is there a better way to add months in DAX?</p>