UK tax system and ethics
Understand the structure of the UK tax system, professional responsibilities and ethical behaviour in tax work.
AAT Level 4 PAT · PTAX
Principles of Taxation
Calculate UK tax liabilities for individuals and companies, understand administration and identify ethical tax-planning opportunities.
Unit overview
Apply the knowledge in a professional context.
New Level 4 PAT qualificationThis page supports the AAT Level 4 Diploma for Professional Accounting Technicians, operational from 1 September 2026. Check that this is the qualification route shown in MyAAT or by your training provider.
PTAX integrates the main taxes affecting UK individuals and trading companies. Learners calculate liabilities, apply current tax-year rules, recognise filing and payment obligations and communicate ethical advice that distinguishes legitimate planning from inappropriate behaviour.
Use this page as a starting point for revision. Work through the topic areas, identify where confidence is lowest and combine independent practice with the downloads and events added for this unit.
Key topics
What to focus on in PTAX.
These summaries provide a revision map rather than a replacement for the current AAT qualification specification and your training-provider materials.
Income and National Insurance
Calculate Income Tax and relevant National Insurance contributions using the applicable rates, bands and allowances.
Sources of income
Identify and calculate employment, self-employment, property, savings, dividend and other relevant income.
Capital Gains Tax
Calculate gains and losses for UK taxpayers and determine the Capital Gains Tax payable.
Corporation Tax
Prepare tax computations for trading companies, including trading income, property, interest and chargeable gains.
Tax administration
Understand records, returns, claims, deadlines, payments, errors, penalties and communication with HMRC.
Tax planning
Identify suitable planning opportunities while maintaining professional standards and explaining the practical consequences.
How to revise this unit
- 1Keep a clearly dated rates-and-allowances sheet and confirm the Finance Act used by your assessment.
- 2Use a standard computation format for each tax and label every adjustment, allowance and relief.
- 3After calculating a liability, add the filing, payment and record-keeping implications.
- 4For advice questions, compare the available options and explain both tax and ethical consequences.
Common pitfalls
- !Using a rate, threshold or allowance from the wrong tax year.
- !Calculating one source of income correctly but failing to combine it properly in the overall computation.
- !Suggesting a tax-saving action without considering anti-avoidance, disclosure or professional ethics.
Free revision posters
Revision posters for PTAX.
Posters published for this unit appear here automatically. Open a poster to view it online or download the PDF for personal study.
Learn live
Upcoming sessions for PTAX.
Published events matching this unit appear automatically. When no direct match exists, the page may show another Level 4 session.
ExamReady
PTAX practice questions and a timed mock, from 27 October.
This is independent revision support and is not produced, endorsed or approved by AAT. Always check the current AAT qualification specification, assessment information and your training-provider guidance.