Expats pay income tax in the UK mainly through the Pay As You Earn (PAYE) system, which is used by most employers. For expats, this means income tax and National Insurance contributions are automatically deducted from their salary before they are paid. Expats in the UK will receive a payslip showing how much tax has been taken and which tax code is being used. Some expats, such as freelancers, contractors, or those with multiple income sources, may need to register for Self Assessment and file an annual tax return. Expats in the UK should also be aware that tax residency rules determine how much of their global income is taxable, and double taxation agreements may apply. Keeping records of income and understanding tax obligations is important, especially in the first year of residence. Many expats choose to seek professional tax advice to ensure compliance and avoid unexpected liabilities.