I need to calculate leavers holiday entitlement where only the number of
fully completed months are included. A month where the start date is after
the first, or a month where the end date is prior to the last day of the
month are not included.

Example: Start Date: 15 January
End Date: 26 June
Full Months: 4 (Feb; Mar; Apr; May)

The start and end dates will be entered into cells;

Is there a definhed function to calculate this or what formula would I need?

Thanks, as always, for any assistance.

Dave