HMRC Expat Self-Assessment SA100 & SA109 Guide 2026

Who Must File Self Assessment as a UK Expat or Non-Resident?

Being an expat or non-UK resident does not by itself create an automatic Self Assessment filing obligation. The obligation depends on the taxpayer's actual income, gains and circumstances, and on whether HMRC has issued a notice to file. Common triggers include untaxed UK rental income, taxable foreign income or gains, chargeable capital gains, self-employment, certain High Income Child Benefit Charge liabilities, and other circumstances specified by HMRC. A person who is only an employee and has no other untaxed income or gains may not need Self Assessment merely because they live abroad or have returned to the UK.

SA100, SA109, SA106, SA105 and SA108: What Each Form Does

An expat Self Assessment return can contain a main SA100 return plus one or more supplementary pages. Which supplementary pages are required depends on the taxpayer's actual circumstances. SA109 is the residence and Foreign Income and Gains (FIG) regime supplementary page for the 2025-26 return; SA106 records foreign income and gains; SA105 records UK property income; and SA108 records capital gains and losses.

SA109 in 2026: Residence, Split-Year and FIG

The 2026 SA109 is no longer simply a 'Residence & Remittance' page. HMRC's current 2026 form is titled Residence and foreign income and gains (FIG) regime etc. It is used to record residence information and relevant FIG-regime information on the SA100 return. If the taxpayer needs to report non-UK residence, dual residence, split-year treatment or make a relevant FIG claim, the SA109 and its notes should be followed for the relevant tax year.

SA109 Online Filing: Commercial Software or Professional Agent

HMRC's 2026 SA109 notes state that the Residence and FIG pages cannot simply be submitted electronically through the standard HMRC online Self Assessment service. If these pages need to be filed online, the taxpayer must use compatible commercial software or authorise a professional agent to file the return. HMRC maintains a list of commercial software suppliers and identifies which suppliers support SA109.

Self Assessment Filing Deadlines for 2025-26

For the 2025-26 tax year, the standard deadlines are 31 October 2026 for paper returns and 31 January 2027 for online returns. The tax year itself runs from 6 April 2025 to 5 April 2026. A taxpayer who needs to register for Self Assessment for the first time generally must notify HMRC by 5 October 2026 for the 2025-26 tax year. The balance of tax for 2025-26 is normally due by 31 January 2027, together with any first payment on account that is due.

Payments on Account and Why the 31 January Amount Can Be Larger

A taxpayer may owe more than the simple balancing payment shown for the tax year because HMRC can require payments on account towards the following year's tax. Generally, payments on account are required where the previous year's Self Assessment tax liability exceeds the relevant threshold and sufficient tax has not already been collected at source, although there are exceptions. Each payment on account is normally half of the previous year's relevant liability.

SA106: Foreign Income, Gains and Foreign Tax Credit Relief

SA106 is used to record foreign income and gains on the SA100 return. Depending on the tax year and circumstances, it can include foreign dividends, interest, pensions, property income and other foreign income or gains, together with relevant foreign tax credit information. The foreign-tax-credit claim is subject to the applicable treaty or unilateral-relief rules and is not automatically equal to every pound of foreign tax paid.

SA105: UK Rental Income for Expats and Non-Residents

UK property income is generally taxable in the UK even where the owner is non-UK resident. SA105 is the supplementary page used to record UK property income. Non-resident landlords can also fall within the Non-Resident Landlord Scheme, under which a letting agent or tenant may have to deduct basic-rate tax unless HMRC authorises gross payment. Approval to receive rent gross does not make the rental income exempt; the landlord still calculates the UK tax liability through Self Assessment where required.

SA108: Capital Gains for UK Property and Other Assets

SA108 is the Capital Gains summary page and can be required where the taxpayer has reportable UK or foreign capital gains. A non-resident can still be within UK CGT on UK land and property, while a UK resident is generally within CGT on worldwide gains subject to applicable reliefs and the FIG regime. The residence status, disposal date and asset type therefore need to be established before deciding whether SA108 is required.

Late Filing Penalties: 2026 Structure

If a Self Assessment return is required and is filed late, HMRC's current penalty structure starts with an initial £100 penalty. After 3 months, daily penalties of £10 per day can accrue for up to 90 days, creating a maximum daily-penalty component of £900. After 6 months, a further penalty of 5% of the tax due or £300, whichever is greater, can apply. After 12 months, another 5% or £300 penalty can apply. These are late-filing penalties and are separate from penalties for paying tax late.

Late Payment Penalties and Interest

Late payment has its own penalty structure. HMRC's current guidance states that penalties of 5% of the tax unpaid can arise at 30 days, 6 months and 12 months after the relevant payment deadline. Interest is also charged on late-paid tax. Therefore a return filed on time can still result in penalties and interest if the tax itself is paid late.

Reasonable Excuse and Penalty Appeals

A taxpayer who files late can appeal a penalty where they had a reasonable excuse. HMRC's current guidance recognises that circumstances are considered according to their facts. A reasonable excuse should explain why the taxpayer could not reasonably comply by the deadline and what they did to remedy the failure once the excuse ended. Simply forgetting the deadline is generally not enough by itself.

2026 Expat Self Assessment Workflow

A reliable expat Self Assessment process begins by determining whether a return is actually required. Once that is established, the taxpayer identifies the correct supplementary pages, determines residence and split-year status, reports UK and foreign income/gains, calculates foreign-tax credit relief where applicable, checks payments on account and submits by the relevant deadline. The final step is verifying both filing and payment rather than treating 31 January as only a filing date.

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