What are Supplementary Self Assessment Pages?

As the name suggests, supplementary pages are additional pages that need to be completed and filed with your main SA100 Self Assessment tax return. They provide summary information about income and expenses from specific taxable sources, enabling HMRC to work out how much tax you owe overall.

Each supplementary page has its own title and number that refers to a specific source of taxable income. The most common ones are:

• SA102 – employees or company directors use an SA102 to report income from employment when submitting an Self Assessment tax return to report other taxable income. A different SA1032 must be used for each job or directorship.
• SA103S – sole traders use the SA103S to report income from self-employment if their annual business turnover was below the VAT threshold (£90,000 for the 2024-25 tax year). If it was above, they need to use the SA103F. If you have more than one source of self-employed income, an SA103 must be used for each.
• SA104S – ordinary business partners use this short version when filing their SA100 if they’re only reporting partnership trading income and interest or alternative finance receipts received after tax was deducted from banks or building societies. Otherwise, the SA104F is used to report full partnership income.
• SA105 – landlords use this to report rental income from UK land and/or property or income from letting furnished holiday accommodation in the UK or EEA.
• SA106 – used to report foreign income/gains or to claim foreign tax credit relief.
• SA108 – taxpayers file the SA108 with their SA100 to report capital gains or losses.
• SA109 – used to report residence and domicile status and claim personal allowances as a non-UK resident for tax. People resident outside the UK but who earn UK rental property must file an SA109.