2021 FORMULA ONE SPORTING REGULATIONS
39.12 If the clerk of the course considers it safe to do so, and the message “LAPPED CARS MAY NOW OVERTAKE” has been sent to all Competitors via the official messaging system, any cars that have been lapped by the leader will be required to pass the cars on the lead lap and the safety car.
This will only apply to cars that were lapped at the time they crossed the Line at the end of the lap during which they crossed the first Safety Car line for the second time after the safety car was deployed.
Having overtaken the cars on the lead lap and the safety car these cars should then proceed around the track at an appropriate speed, without overtaking, and make every effort to take up position at the back of the line of cars behind the safety car. Whilst they are overtaking, and in order to ensure this may be carried out safely, the cars on the lead lap must always stay on the racing line unless deviating from it is unavoidable. Unless the clerk of the course considers the presence of the safety car is still necessary, once the last lapped car has passed the leader the safety car will return to the pits at the end of the following lap.
If the clerk of the course considers track conditions are unsuitable for overtaking the message “OVERTAKING WILL NOT BE PERMITTED” will be sent to all Competitors via the official messaging system.