Not sure this is what you want but if you put this code
into the commandbutton, it'll add 8% to the value in D33

Private Sub CommandButton1_Click()
Range("d33") = Range("d33").Value * 1.08
End Sub

-----Original Message-----
I'm trying to add tax (8%) to a cell (D33) based on a
COMMAND BUTTON (cell C33)
PLEASE help. I've never used Macro's before and I'm
loosing way to much sleep over this!
.