Who must file a Self Assessment tax returnWho needs a Self Assessment return for 2025 to 2026: sole traders over £1,000, partners, landlords, capital gains, the child benefit charge and untaxed income.Registering a client for Self AssessmentThe 5 October registration deadline, registering sole traders, partners and others, forms CWF1, SA1, SA400 and SA401, and when the UTR arrives.Self Assessment payments on accountWhen payments on account are due, the £1,000 and 80% tests, the 31 January balancing payment, reducing them with SA303, and a worked example.Self Assessment deadlines and penalties for 2025 to 2026Paper returns by 31 October 2026, online by 31 January 2027, the £100 and £10 daily penalties, late payment penalties at 5% and HMRC interest.SA103S or SA103F for self-employmentWhen a sole trader uses the short SA103S or the full SA103F pages for 2025 to 2026, the £90,000 turnover limit, and what the full pages add.The £1,000 trading and property allowancesHow the £1,000 trading allowance and property allowance work, partial relief against expenses, who cannot claim them, and when to tell HMRC.The residential property finance cost restrictionHow section 272A ITTOIA 2005 restricts mortgage interest relief for landlords, the 20% basic rate tax reduction, carry forward and worked examples.The High Income Child Benefit ChargeThe High Income Child Benefit Charge from 2024 to 2025: the £60,000 and £80,000 thresholds, 1% per £200, paying through PAYE, and opting out.Capital Gains Tax on UK property and the 60-day returnThe 60-day report and pay deadline for UK property, the UK property account, 2026 to 2027 rates and allowance, private residence relief and non-residents.Basis period reform and transition profitsThe tax year basis for sole traders and partners from 2024 to 2025, the 2023 to 2024 transition year, transition profit spread over 5 years and overlap relief.
Self Assessment
Self Assessment for practitioners: who must file and register, payments on account, deadlines and penalties, the self-employment pages, the trading and property allowances, finance costs for landlords, the High Income Child Benefit Charge, capital gains on UK property and the move to the tax year basis.