How surcharging works on your terminal depends on the Shift4 EFTPOS solution you chose.
For Shift4 Low Cost EFTPOS customers, every Shift4 terminal purchase automatically adds a surcharge. This amount is calculated for you and displayed on the screen for your customers: they will see the total amount owed, including the surcharge. If you wish to bypass a surcharge, read about how to do so here.
If you are a Simple Flat Rate customer, you are paying your merchant service fees, which will be charged to you automatically at the end of the month. For more about your specific plan, contact your account manager.