Because both Poland and Germany are members of the Schengen Area, there are typically no permanent border controls, and citizens of EU countries can travel between them using only a National ID Card. However, for 2026 travel, it is highly recommended to carry a passport or valid ID at all times, as "temporary" border checks are frequently reinstated for security or immigration management. Non-EU citizens must carry their passport and, depending on their nationality, a valid Schengen visa or residency permit. Even without a formal border crossing, airlines and international bus companies (like FlixBus) require a valid government-issued photo ID to board. Failure to produce a valid travel document during a random spot check can lead to fines or being denied entry into Germany.