There is no airport in Monaco (nearest one is in France, Nice Airport) only a helioport. There are no duty free arrival shops there but there is a duty free shop on departure. There is however a VAT tax there and also a tax on alcohol in Monaco itself. You can see details on this web link http://www.dutyfreeonarrival.com/en/travelpoint/378?PHPSESSID=61c31c103a5ba0980db8708e5e7aaedf