What Saudi Arabia does and does not tax
For an employee, Saudi Arabia is close to tax free. There is no personal income tax on salaries or wages, no personal capital gains tax and no inheritance or estate tax on individuals, and that applies to Saudi nationals and British expatriates alike. Nothing is deducted from an expatriate's own pay for social insurance either: expatriates do not contribute to GOSI from their salary, and the employer pays a 2% occupational-hazard contribution instead. The taxes people associate with the Kingdom, zakat and corporate income tax, fall on businesses rather than employees, so a salaried professional sits outside both. Your gross salary is broadly your net salary, which is why Riyadh, Jeddah and NEOM have become such popular postings. The full picture is in our moving to Saudi Arabia tax guide.
The tax you can still pay is UK tax
Tax free in Saudi Arabia does not mean tax free everywhere. Until you become non-resident under the UK Statutory Residence Test, the UK taxes your worldwide income, and that includes the Saudi salary you thought was untouched. Residence is a test, not a choice: an Iqama and a Saudi employment contract prove where you live and work, but they do not make you UK non-resident. Most people moving for a full-time job rely on the third automatic overseas test: full-time work abroad across the tax year, fewer than 91 days in the UK and fewer than 31 UK workdays. Leave partway through a tax year and you also need split-year treatment, usually Case 1 (starting full-time work overseas) or Case 3 (ceasing to have a UK home), or the whole year can be taxed as UK resident.
What stays UK-taxable after you are non-resident
Once you are correctly non-resident the UK taxes only UK-source income and gains on UK land. Rent from a UK property stays taxable under the Non-Resident Landlord Scheme, so you file a UK return every year, and a later sale of UK residential property carries Non-Resident Capital Gains Tax at 24% or 18%, reported and paid within 60 days of completion. Two longer tails matter too. Return within five years, having been UK resident in at least four of the seven tax years before you left, and gains and certain dividends taken while abroad can be taxed in the year you come back. And because UK inheritance tax is now residence-based, a long-term UK resident can remain within UK IHT for between three and ten years after leaving. Our Statutory Residence Test guide covers the day counts.