Guides to UK Self Assessment
Plain-English guides to Self Assessment deadlines, payments on account, late-filing penalties, Income Tax rates, Class 2 and Class 4 National Insurance, tax codes and filing online for free with HMRC.
Self Assessment deadlines for 2026 and 2027
Official HMRC deadlines for the 2025/26 Self Assessment tax year: paper (already passed), pay through a tax code by 30 December 2026, and file and pay online by 31 January 2027.
What are payments on account?
A plain-English guide to Self Assessment payments on account: when they are due, the official £1,000 and 80% tests, balancing payments, and how to ask HMRC for a reduction.
Self Assessment late filing and late payment penalties
How HMRC’s official late-filing and late-payment penalties work, including the £100 charge, £10 daily penalties, the 5% or £300 steps, interest, and failure to notify.
UK Income Tax rates for 2025/26 and 2026/27
Official UK Income Tax bands and dividend rates for 2025/26 and 2026/27, including the Scottish starter-band change and the rise in ordinary and upper dividend rates.
Self-employed National Insurance: Class 2 and Class 4
Official Class 2 and Class 4 National Insurance figures for self-employed people, including the 2025/26 Small Profits Threshold of £6,845 and the 6% / 2% Class 4 rates.
Who needs to file a Self Assessment return?
Who must send a UK Self Assessment return, official reasons including self-employment over £1,000, partners, Capital Gains Tax and the High Income Child Benefit Charge, and how to check.
Student loan repayments and Self Assessment
How UK student loan repayments work if you are self-employed or already complete a Self Assessment return, with official 2025/26 and 2026/27 plan thresholds.
UK tax codes explained
What UK tax code letters and numbers mean, including 1257L, emergency codes for 2025/26 and 2026/27, Scottish and Welsh prefixes, Marriage Allowance M and N, and K codes.
The Personal Allowance taper over £100,000
How the UK Personal Allowance is reduced by £1 for every £2 of income above £100,000 in 2025/26 and 2026/27, why it reaches zero at £125,140, and what that does to Income Tax.
How to file a Self Assessment return online for free
How to register for Self Assessment and file a UK tax return online for free with HMRC, what you need, who cannot use the free service, and where paid software fits in.
Dividend tax in 2026/27: what changed from 2025/26
How UK dividend tax changes in 2026/27: the ordinary rate rises to 10.75% and the upper rate to 35.75%, while the additional rate and the £500 dividend allowance stay the same.
The High Income Child Benefit Charge, in official figures
Official High Income Child Benefit Charge rules from 2024/25: the £60,000 threshold, 1% of Child Benefit for every £200 of income, and full withdrawal at £80,000.