title: How to include month and year in arrayformula sumif statement
body: <p>I have the following code which I'm using in my Google Spreadsheet.</p>
  
  <pre><code>=ArrayFormula(sumif(month(income!A$2:A), month(A2) , income!B$2:B))
  </code></pre>
  
  <p>There are two sheets, main and income. </p>
  
  <p>Income sheet contains payments received in every month. (there are multiple payments in each month). So I sum up earnings in a month and display them as monthly earning in main sheet.</p>
  
  <p>The problem is - since it only considers month, when we have april 2014 and april 2015, the total sum for april in main sheet counts both years.</p>
  
  <p>I am trying to figure out how to use year+month in the formula. Any help?</p>