What is the mandatory time interval for performing the vehicle roadworthiness test for coaches and buses?

For coaches and buses in Germany, a roadworthiness inspection (Hauptuntersuchung or HU) must be performed every 12 months. This rule exists because buses and coaches transport many passengers and usually cover long distances, so regular checks are crucial to ensure safety. The annual inspection checks all vital parts, such as brakes, lights, steering, and the condition of the vehicle, to prevent accidents and technical problems. For cars, the interval is usually every two years, but for buses and coaches, the law sets a stricter schedule of every year due to their higher safety requirements. So, the correct interval is every 12 months.