title: Why does add months calculate incorrectly when adding a month in the october and november timeframe in SharePoint workflows?
body: <p>I have a simple workflow that adds one month to a date. Whenever the inputted date is between 10/5 and 11/4, the workflow calculates incorrectly. For example, if I input 10/4/2018, the workflow correctly calculates to 11/4/2018. If I use 10/5/2018, the workflow incorrectly calculates to 11/4/2018. This same incorrect result continues if I keep incrementing the input date up to 11/4/2018 (output is 12/3/2018). When I input 11/5 as the input date, the workflow goes back to correctly calculating and returns 12/5. As far as I can tell, the year does not matter (i.e. same issue if I did the same test using dates in 2019). Has anyone experienced this odd behavior? </p>
  
  <p>To add to my comment where I do not see ISO Formatted, here are pics of my SharePoint 2013 workflow and what I see when I go to set the variable:</p>
  
  <p><a href="https://i.stack.imgur.com/XpV2j.jpg" rel="nofollow noreferrer">Workflow</a></p>
  
  <p><a href="https://i.stack.imgur.com/o022Y.jpg" rel="nofollow noreferrer">Variable assigment</a></p>