The poll tax riots were a series of riots in British towns and cities during protests against the poll tax (officially known as the "Community Charge"), introduced by the Conservative government of Prime Minister Margaret Thatcher. The largest protest occurred in central London on Saturday, 31 March 1990, shortly before the tax was due to come into force in England and Wales.
The advent of the poll tax was due to an effort to alter the way the tax system was used to fund local government in Britain. The system in place until this time was called "rates" and had been in place in some form from the beginning of the 17th century. The rates system has been described as "a levy on property, which in modern times saw each taxpayer paying a rate based on the estimated rental value of their home."
The Thatcher government had long promised to replace domestic rates, which were unpopular, especially among Conservative voters. They were seen by many as an unfair way of raising revenue for local councils. It was levied on houses rather than people.
The proposed replacement was a flat-rate per capita Community Charge - "a head tax that saw every adult pay a fixed rate amount set by their local authority." The new Charge was widely called a "poll tax" and was introduced in Scotland in 1989 and in England and Wales a year later. The Charge proved extremely unpopular: while students and the registered unemployed had to pay 20%, some large families occupying a relatively small house saw their charges go up considerably, and the tax was thus accused of saving the rich money and moving the expenses onto the poor.
In November 1989 the All Britain Anti-Poll Tax Federation was set up by the Militant tendency. Other groups such as the 3D (Don't Register, Don't Pay, Don't Collect) network provided national coordination for anti poll tax unions who were not aligned to particular political factions. The All Britain Federation called a demonstration in London for 31 March 1990 which all of the major networks organised for. Three days before the event, organisers realised the march would be larger than 60,000 (the capacity of Trafalgar Square) and asked permission from the MPS and the Department of the Environment to divert the march to Hyde Park. The request was denied on the basis that the policing had been arranged for Trafalgar Square and there was no time to re-plan it. A building site on Trafalgar Square with easily accessible supplies of bricks and scaffolding was left largely unsecured while the police set up their centre of operations on the other side of the square.