The UK Tax System and Tax Administration
The architecture of UK tax
Candidates must know the difference between tax law (statute, chiefly the annual Finance Acts) and tax practice (HMRC guidance, statements of practice, extra-statutory concessions). Note the constitutional convention that taxes are renewed annually, and know the roles of the main bodies: HMRC (collection and administration), the Treasury (policy), and the tribunals/courts (appeals). Understand the tax year (6 April to 5 April for individuals) versus the financial year (1 April to 31 March for corporation tax rates).
Self assessment mechanics
Learn the filing and payment timetable for individuals: return due 31 January following the end of the tax year; payments on account (each half of the prior year's liability net of tax deducted at source) due 31 January and 31 July, with any balancing payment also on 31 January. Know the penalties for late filing (£100, then escalating) and late payment (5% of unpaid tax at 30 days, 6 months, 12 months). Understand discovery assessments, enquiries, and the appeal route to the First-tier and Upper Tribunals.
Traps
Questions often test the payment on account threshold (liability over £1,000 and less than 80% collected at source), the interplay of interest and penalties (both can apply), and the distinction between a determination (HMRC may issue one if no return is filed) and an assessment. Watch the date arithmetic on 31 January/31 July.
Rule of thumb
Payments on account are each 50% of the previous year's relevant liability; if that liability was nil or below £1,000, no POA arise.
Worked example: 2023/24 liability £4,000, all from employment taxed at source at 60%. POA for 2024/25 are each £2,000 (31 Jan 2025 and 31 Jul 2025), because the relevant amount exceeds £1,000 and less than 80% was collected at source.