Whether you must recheck your bag after customs depends on your first point of entry and your final destination. When arriving in the United States from an international location, even if you have a connecting flight on a single ticket, you must physically collect your checked luggage, walk it through the Customs and Border Protection (CBP) checkpoint, and then drop it off at a nearby "Baggage Transfer" belt. However, in many other regions like the European Schengen Area, if your bags are "checked through" to your final destination, you usually only clear immigration at your first stop and your bags are automatically transferred to your final stop where you clear customs. In the UK, the rules vary; generally, if you are connecting from an international flight to a domestic one, you may need to reclaim and recheck. Always look at the luggage tag printed at your initial departure; if it lists your final destination and not just the layover city, it is likely "checked through," but you should still confirm with the agent at the first check-in desk.