Thanks for clarifying.  That works ... sort of.  If I run a report for a multi-year time period, and sort by total balance, I can get customers with no sales at all to appear at the top of the list.  Then I guess I can work through eliminating one year at a time to narrow things down.

It would be so much easier to have a filter for "no invoices after xxx date" ... but this gets close enough for what I need.

Thanks.