Income tax is often viewed as a permanent feature of the UK tax system, but historically it began as a temporary wartime measure. Its origins lie at the end of the eighteenth century, when the British government faced the enormous cost of financing the war against Napoleonic France.
The first modern income tax was introduced in 1799 by Prime Minister William Pitt the Younger. Britain was engaged in the Napoleonic wars and government borrowing alone was not sufficient to fund the military effort. Pitt therefore introduced a tax on income to raise additional revenue.
Under the original legislation, individuals with annual incomes of £60 or more became liable to tax. The rate of tax was two shillings in the pound on the highest band of income. As there were twenty shillings in a pound, two shillings represented 10 per cent of taxable income. In effect, therefore, the earliest version of UK income tax imposed a top rate of around 10 per cent.
The threshold of £60 per year was significant at the time. In the late eighteenth century this level of income placed a person comfortably above the earnings of most labourers and agricultural workers. Converting historic values into modern terms is always approximate, but using general inflation measures, £60 in 1799 is broadly equivalent to between £6,000 and £8,000 today. If the comparison is made using relative earnings or economic share of national income, the modern equivalent could be considerably higher, potentially in the region of £15,000 to £20,000 or more. Either way, the tax was clearly aimed at individuals who were relatively well off by the standards of the period.
The original income tax did not remain in place continuously. It was abolished in 1816 following the defeat of Napoleon, partly because it had been introduced as a temporary wartime measure and had never been particularly popular. However, the concept had been established, and income tax returned in 1842 when Sir Robert Peel reintroduced it to deal with government budget deficits.
Today, income tax has become one of the largest sources of government revenue in the United Kingdom. For the 2025-26 tax year, individuals generally pay no income tax on the first £12,570 of taxable income due to the personal allowance. Income above that level is taxed at 20 per cent for basic rate taxpayers up to £50,270. Higher rate taxpayers pay 40 per cent on income between £50,270 and £125,140, and the additional rate of 45 per cent applies to income above £125,140.
Compared with the original 10 per cent rate introduced in 1799, modern income tax rates are substantially higher. However, the structure of the system is also far more complex, with multiple bands, reliefs and allowances.
What began as a temporary wartime measure to fund the fight against Napoleon has therefore evolved into a central pillar of the UK fiscal system, shaping government finances and personal tax planning for more than two centuries.
