I currently use the formula to calcualte the $$ earned by employee ( note
the data is captured monthly in multiple sheets in a workbook. 1 sheet per
month)

=SUMPRODUCT(('2004-JAN_05'!$C$2:$C$20000=$A36)*('2004-JAN_05'!$J$2:$J$20000<0)*'2004-JAN_05'!$J$2:$J$20000)

note: 2004-JAN_05 is one sheet

I need help with a formula that will track the number of days worked by
employee referenced to each sheet.

Thanks