I am trying to add the ISERROR to the below formula. I am calculating between dates to return a value or sum the amount of months in between and when $I$2 (which is the current period) is greater than D6 (period end) I get the #NUM! error. I am guessing this is because it is returning a minus which it doesn’t like. If I ca return this as a 0 then my spreadsheet will work.