When you're driving a passenger car, is it permissible to overtake a bus beyond this sign?

In the picture, the round sign with a red border and two cars - a red one on the left and a black one on the right - is B-25 "no overtaking". When driving a passenger car, you are not allowed to overtake a bus beyond this sign. The answer is: no.

The Regulation on road signs and signals states that sign B-25 "no overtaking" prohibits drivers of power-driven vehicles from overtaking power-driven multi-track vehicles. A passenger car is a power-driven vehicle, so the ban is addressed to you, and a bus is a power-driven multi-track vehicle, so it is covered by the ban - both conditions are met, and overtaking a bus beyond sign B-25 is prohibited. The fact that the bus is moving slowly does not matter; the sign is placed where overtaking is dangerous because there is not enough visibility or space. Beyond sign B-25 you may overtake only vehicles that are not power-driven multi-track vehicles, for example a bicycle, a moped, a motorcycle without a sidecar, an electric scooter or a horse-drawn vehicle. The ban applies until the nearest junction, unless sign B-27 "end of no overtaking" or B-42 "end of prohibitions" cancels it earlier. Plate T-23 under sign B-25 means that the ban applies only to drivers of the vehicle shown on the plate; without the plate, it applies to all power-driven vehicles.

Legal basis: § 23 para. 1, 2 and 4 and § 32 para. 1 and 2 of the Regulation on road signs and signals; Art. 2 point 32 of the Road Traffic Act (Prawo o ruchu drogowym)