While Standard DSO measures current and overdue invoices, Best Possible Days Sales Outstanding (or Best DSO) measures only current invoices. Tracking the delta between Best DSO and Standard DSO will ensure that you are optimizing your business’ account receivable (AR) management practices and help identify opportunities to improve cash flow. Quarter-over-quarter or year-over-year reductions in this delta is a key performance indicator (KPI) of AR improvement - and the financial health of your company.