Would appreciate some expert assistance in solving a problem I am having in writing a formula that will sum data for a 12 month period that is not based on a calendar year. For example may have data starting in June 2011 running to date, but not every month. If I set a start date for Year 1, say April 2012, I need to see Year 0 numbers (anything prior to April 2012), Year 1 numbers (April 2012 to March 2013), Year 2 numbers (April 2013 to March 2014), and so on. Date format is currently mmm-yy.

If this could be performed via a macro which references the database (spreadsheet), then even better. The database will contain multiple columns, of which two will contain the date and corresponding number respectively.

Many thanks in advance