- noun the process in which an individual taxpayer calculates his or her own tax liability and reports it to the Inland Revenue which then issues a notice to pay
- noun a system where each taxpayer is required to fill in his or her tax return and calculate how much tax is owed for the period. Taxpayers in the UK are given a period of five months (6 April to 30 September) during which they can submit details of their income and allowances for the previous tax year (i.e. to 5 April) and get the local tax office to prepare their assessment for them. After that period, taxpayers must do the calculations themselves. Taxpayers may receive penalties in the form of fines, for late filing of tax returns.
- noun a systematic and regular review of its own activities carried out by an organisation, which compares the results against a model of excellence