Yes, you must pass through both Immigration (Passport Control) and Customs when arriving in London from outside the UK. In 2026, the process is highly streamlined for citizens of the US, Canada, Australia, and the EU, who can typically use the e-gates to scan their biometric passports. After clearing immigration, you collect your checked luggage and proceed to the Customs hall. Most travelers follow the "Green Channel" (Nothing to Declare), which involves walking through a specific exit. While you may not see an officer, you are legally declaring that you are not carrying prohibited items or goods exceeding duty-free allowances. If you have restricted items, commercial goods, or more than £10,000 in cash, you must use the "Red Channel" to make a formal declaration. In 2026, the UK Border Force also uses "passive" technology, such as X-ray and thermal scanning, as you walk through the green channel to ensure compliance without stopping every passenger.