Abstract: In an apparatus for accurately counting a stack of documents and especially legal tender (i.e., paper money), tests for authenticity are performed simultaneously with the counting operation and without in any way impeding the type of counting operation being performed. At the same time that the counting operation is being performed, at speeds of the order of 1250 bills per minute, each bill or note currency is tested for certain properties of genuineness, including fluorescence and magnetic characteristics. Notes which fail to satisfy the tests are categorized as suspect notes and automatically stop the machine and thereby temporarily halt the counting operation. The suspect note is isolated as the top-most document in the outfeed stacker greatly facilitating the handling and removal of the suspect bill for further examination.