Congestion charges in London are part of the "London Congestion Charge" system, wherein certain categories of vehicle are charged a fee to operate during certain times of the day, also known as the "Congestion Charge Zone." The system endeavors to accomplish two distinct aims. One is to reduce congestion; the other is to raise revenue for public transportation.
The standard fee for vehicles operating in the CCZ is 10 a day, for every day that the vehicle operates in the zone from 7am to 6pm Monday through Friday. There is a stiff penalty of up to 180 for not paying the initial fee. The payment system is mostly automated.
Some vehicles are granted exemptions from the congestion charges of London. These vehicles include buses, very small vehicles, fire engines, police vehicles, minibuses, taxis, ambulances, vehicles run on alternative fuels and bicycles. Citizens who live in the zone may receive a sizeable discount if they pay at once for a week or more.
There has been some amount of controversy regarding the avoidance of payment by some outside government agencies. For example, in 2005 the United States and Germany embassies did not pay the congestion charge because they argued that it was a tax, which under the Vienna convention foreign embassies are protected from. However, other embassies did pay the charge. As of 2011, the United States owes around 5.5 million in back charges.
In the event of an emergency, or some other public need, the London authorities can actually suspend the Congestion Charge Zone. For example, the CCG was suspended in 2005 after the terrorist attack on London transport.
There are different tactics afoot for avoiding paying the fee, and enforcement fees have been shown to serve as a major element of the overall revenue collected via the Congestion Charge Zone. One tactic has been to copy license plates, so that the owner of the original one receives double charges when they have not been in the CCG. In response to this, the authorities have begun to keep a database the records these instances of double charging.
London congestion charges are a main form of revenue for public transportation and also a means of keeping congestion down. It has proven difficult to enforce in some ways, like the case of the US and Germany embassies. There has also been some amount of fraud as well.