Whether you need a visa for a connecting flight in Germany depends on your nationality and the nature of your transit. If you are from a country that requires a Schengen Visa, you may need an Airport Transit Visa (ATV) even if you do not leave the "international transit area" of the airport. However, many nationalities (including citizens of the US, UK, Canada, and Australia) can transit through German airports without a visa as long as they stay in the transit zone and their final destination is outside the Schengen Area. A critical distinction in 2026 is whether you have to leave the transit area to collect and re-check bags (often the case with "self-transfer" bookings on budget airlines). If you have to pass through immigration to reach the check-in desk, you will need a full Schengen Visa or an ETIAS authorization (for visa-exempt citizens). Additionally, if your connecting flight is to another city within the Schengen Area (e.g., Frankfurt to Rome), you must pass through immigration in Germany, meaning you must be legally authorized to enter the Schengen zone.