in the workbook module you can put this, the example checks each tab any time
one is clicked and sets its colorindex to the value in M20. Colorindex
requires a number but you can play with it to get it how you want it.
Private Sub Workbook_SheetActivate(ByVal Sh As Object)
For i = 1 To Sheets.Count
Sheets(i).Tab.ColorIndex = Cells(13, 20)
Next
End Sub
Or to go off of the value you can hard code something like
Private Sub Workbook_SheetActivate(ByVal Sh As Object)
For i = 1 To Sheets.Count
if Sheets(i).Cells(13, 20)<=0 then Sheets(i).Tab.ColorIndex = 3
if Sheets(i).Cells(13, 20)>0 then Sheets(i).Tab.ColorIndex = 4
Next
End Sub
change the number to change the color

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-John
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