When one filters on DATE in SUPBAL, RamBase looks at the DATE of the invoice. When you filter on PERIOD, RamBase looks at the value in the PERIOD field of the invoice. An invoice can have a date in one month and posted in the following month and therefore different period giving different results. This is standard functionality in RamBase, in all financial reports and programs for example: CUSBAL (Customer balance)SUPBAL (Supplier balance)INVBAL  (Inventory balance)PROBAL (Product balance)