income tax
A direct tax on a person’s income, including employment income, investment income, and the profits from unincorporated trading and property businesses. The amount of tax is based on a person’s entire income for the year, less certain personal allowances, on a progressive scale. Income tax is not a permanent tax, but has been imposed by the year’s Finance Act each year since 1799, except 1816–41.

A company not resident within the UK is subject to income tax, and not to corporation tax. Corporate bodies acting as trustees are also subject to income tax.

Several systems of deducting tax at source apply. These include Pay As You Earn and the Construction Industry Scheme. Tax not deducted at source is assessed by the taxpayer under the self-assessment system. The tax thus self-assessed is collected in a balancing payment on 31 January following the tax year, although many taxpayers are required to make payments on account on 31 January and the following 31 July.

• Ombudsman
• omission
• omnia praesumuntur rite et solemniter esse acta
• on all fours with
• onomastic
• onus of proof
• onus probandi
• open contract
• open court
• open for signature
• opening speech
• open procedure
• open space
• open the floodgates
• operative mistake
• operative part
• operative words
• opinio juris
• opinion
• opinion evidence
• OPSI
• option
• optional clause
• option to purchase
• oral agreement