The UK Tax System Explained for Internationally Mobile Individuals

The UK tax system is one of the most developed — and complex — in the world. It has evolved over centuries, with layers of primary legislation (Acts of Parliament), secondary legislation (Statutory Instruments), and case law that together create a body of tax law running to thousands of pages. For an internationally mobile individual — whether a British expat considering returning, a non-UK citizen considering working or investing in the UK, or a globally mobile executive with UK connections — understanding the basic architecture of UK taxation is the essential foundation for sensible financial planning.

This guide provides a practical overview of the main UK taxes and how they interact, with particular attention to the rules applying to non-residents and internationally mobile individuals.

The Fiscal Year

The UK tax year runs from 6 April to 5 April — an unusual date that derives from the conversion from the Julian to the Gregorian calendar in 1752. All UK income tax assessments, allowances, reliefs, and most other tax obligations are calculated by reference to tax years, not calendar years.

For self-assessment purposes, the tax year ending 5 April 2026 is "2025/26". Returns for 2025/26 must be filed (if submitted online) by 31 January 2027.

Income Tax

Rates and Bands

UK income tax applies to most types of income received by UK residents: employment income, self-employment income, rental income, pension income, interest, and (at different rates) dividends.

The main income tax bands for 2024/25 (England, Wales, and Northern Ireland — Scotland has its own devolved rates):

Income	Rate
Up to £12,570 (Personal Allowance)	0%
£12,571 to £50,270	20% (Basic rate)
£50,271 to £125,140	40% (Higher rate)
Above £125,140	45% (Additional rate)

Personal allowance taper: the personal allowance is reduced by £1 for every £2 of adjusted net income above £100,000, reaching zero at £125,140. This creates an effective 60% marginal rate between £100,000 and £125,140.

Scottish income tax: Scottish residents pay Scottish rates on non-savings income. Scotland has additional rate bands (19% starter rate, 20% basic, 21% intermediate, 42% higher, 47% top rate — figures change regularly). Always verify current Scottish rates for Scottish residents.

Non-Savings, Savings, and Dividend Income

Income is taxed in a specific order: non-savings income first (employment, rental, pensions), then savings income (interest), then dividends. This ordering affects the rate applied to savings and dividends.

• Savings: basic rate savings income may be covered by the Personal Savings Allowance (£1,000 for basic rate taxpayers, £500 for higher rate, £0 for additional rate)
• Dividends: taxed at 8.75% (basic), 33.75% (higher), 39.35% (additional rate) with a £500 Dividend Allowance (2024/25)

Non-Residents and Income Tax

Non-UK residents are subject to UK income tax only on UK-sourced income. Sources include:

• UK employment income (wages for work performed in the UK)
• UK rental income (from UK property)
• UK pension income (state pension and certain occupational pensions)
• Interest from certain UK sources
• UK trading income (if a permanent establishment exists)

Non-residents do not pay UK income tax on foreign income. The UK personal allowance is available to non-residents from EEA countries and countries with which the UK has a relevant DTA — but not universally.

National Insurance Contributions

National Insurance (NI) is a contributory tax on earnings and profits, technically separate from income tax. It funds the state pension and certain state benefits.

Class 1 (employees): paid by employees on earnings between the Primary Threshold (£12,570/year) and the Upper Earnings Limit (£50,270). Rate: 8% (reduced from 12% in January 2024; verify current rate). Above £50,270: 2% (reduced from 2%).

Class 1 employer contributions: employers also pay NI on employee earnings above the Secondary Threshold. Rate: 15% from April 2025 (increased in the 2024 Autumn Budget). This is a business cost, not deducted from employee pay.

Class 2 and 4: paid by self-employed individuals on profits.

Non-residents: NI obligations depend on the nature of work and whether the individual is employed by a UK entity. Double social security agreements (separate from DTAs) may modify the position.

NI contributions affect entitlement to the state pension. UK citizens who have lived and worked abroad for extended periods often have gaps in their NI record. These can be filled by voluntary Class 3 NI contributions, which are relatively inexpensive and can materially increase the eventual state pension.

Capital Gains Tax

CGT applies to gains on disposal of assets. Key rates and rules:

• Residential property: 18% (basic rate), 24% (higher/additional rate) — increased from 18%/28% and then reduced, with rates having changed multiple times; verify current rates before transacting
• Other chargeable assets (shares, business assets, etc.): 10% (basic rate), 20% (higher/additional rate)
• Business Asset Disposal Relief (BADR): 10% on lifetime gains up to £1 million (formerly Entrepreneurs' Relief, reduced lifetime allowance in 2020)
• Annual exemption: £3,000 (2024/25) — reduced from £12,300

Non-residents are subject to UK CGT on UK property (since April 2015 for residential; April 2019 for commercial) under the NRCGT regime. Non-residents are generally not subject to UK CGT on other UK assets (shares in UK companies, etc.) unless they carry on a UK trade through a permanent establishment.

Inheritance Tax

IHT is charged at 40% on the value of a deceased's estate above the nil-rate band (£325,000 per person) and the residence nil-rate band (£175,000, available against a main residence passing to direct descendants, subject to conditions).

For a married couple, both bands can be combined, giving a potential £1 million threshold.

Domicile and IHT: UK-domiciled individuals pay IHT on worldwide assets. Non-UK domiciled individuals pay IHT only on UK-sited assets. However, long-term UK residents (broadly, those who have been resident in the UK for 10+ of the previous 20 tax years under the new post-2025 rules) are treated as UK-domiciled for IHT even if not domiciled under general law.

This is a crucial consideration for internationally mobile individuals: extended UK residence can create UK IHT exposure on worldwide assets.

Gifts made during lifetime are potentially exempt from IHT if the donor survives seven years. Business Property Relief (BPR) exempts qualifying business assets at 100% after two years. Agricultural property attracts Agricultural Property Relief (APR).

Value Added Tax (VAT)

VAT is charged on the supply of goods and services by VAT-registered businesses. Standard rate: 20%. Reduced rate: 5% (domestic energy, children's car seats, certain services). Zero rate: 0% (most food, children's clothing, books, transport).

Businesses with taxable supplies above the registration threshold (currently £90,000 per year, though this changes — verify the current threshold) must register for VAT. Non-resident businesses supplying goods or services to UK customers may also have UK VAT obligations.

For property: commercial property sales are generally exempt from VAT (though the seller can opt to tax). Residential property sales are not subject to VAT. New residential builds are zero-rated.

Corporation Tax

UK companies pay corporation tax on their profits. The main rate from April 2023 is 25% (for profits above £250,000). Small profits relief applies to companies with profits under £50,000 (19% rate).

Non-UK companies carrying on a trade in the UK through a permanent establishment are also subject to UK corporation tax on the UK-attributable profits.

Dividends paid from a UK company to a non-resident shareholder may be subject to withholding tax under UK domestic law (currently 0% for most dividends — the UK does not routinely apply withholding tax on dividends), modified by DTAs.

PAYE and Self-Assessment

PAYE (Pay As You Earn): most employment income is taxed at source through the PAYE system. The employer deducts income tax and NI before paying the employee's net wage. For straightforward employment situations, no further action may be needed.

Self-Assessment: individuals with more complex tax affairs must file an annual self-assessment return. This includes:

• The self-employed
• Those with rental income
• Higher and additional rate taxpayers (in some circumstances)
• Anyone with offshore income or assets
• Non-residents with UK income
• Individuals with CGT disposals

Self-assessment returns for a given tax year must be filed by 31 October (paper) or 31 January (online) following the year end. For example, the return for 2025/26 (ending 5 April 2026) must be filed online by 31 January 2027. Tax is also due on 31 January, with payments on account (interim payments) on 31 January and 31 July.

HMRC and Penalties

HMRC (His Majesty's Revenue and Customs) administers UK direct and indirect taxes. HMRC has extensive investigation powers and an increasing ability to access financial data from third parties (banks, online platforms, overseas tax authorities through the Common Reporting Standard).

Key penalties:

• Late filing: automatic £100 penalty for a return more than one day late; escalating penalties thereafter
• Late payment: 2.75% per year on unpaid tax (standard interest rate as of 2024/25; check current rate)
• Inaccuracies: penalties of 15–100% of unpaid tax for errors, depending on whether they are careless, deliberate, or deliberate and concealed
• Failure to notify: penalties for failing to notify HMRC of a new tax liability (e.g., becoming a UK resident without registering)

HMRC's Connect system uses data analytics to identify mismatches between declared income and known financial activity. Non-disclosure is increasingly difficult to sustain.

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UK tax law is complex and changes frequently. This article provides a general overview as of mid-2026. Always seek qualified professional advice for your specific circumstances before taking any action.

How Global Investments can help

Navigating the UK tax system as an internationally mobile individual requires a clear understanding of which taxes apply, when obligations arise, and how UK and overseas tax rules interact. Global Investments works with clients to ensure UK tax compliance is maintained without paying more than legally required — through proper self-assessment, DTA analysis, and integrated tax and financial planning. Contact our team to discuss your UK tax obligations.