Self Assessment tax return supplementary pages: which ones should you file?

If you’re new to Self Assessment, perhaps because you’ve just gone self-employed or you’ve recently become a landlord, your knowledge of tax returns will be somewhat limited. That’s OK, because your knowledge will increase the more you fill out and file your annual Self Assessment tax returns.

But long before you have to file your first one to report your annual taxable earnings to UK tax authority HMRC, you should at least know a few basics about the SA100 and Self Assessment tax return supplementary pages, so you know which one(s) to fill out.

Need to know! If you haven’t submitted a tax return before, you must first register for Self Assessment. If you’ve registered before, but did not send a tax return last year, you must register again to reactivate your account.    

What is the SA100?

The SA100 Main Tax Return is eight-pages long and as the name suggests, it is the main part of the Self Assessment tax return. You use it to report (where relevant) details of student loan repayments, taxable income from interest, dividends, UK pensions and annuities, sums paid into pension schemes and any charitable donations you’ve made.

Need to know! If relevant, you also use the SA100 to claim Marriage Allowance or Blind Person’s Allowance, claim a tax repayment or if you earn more than £60,000 a year (2024/25) and you need to report Child Benefit you’ve received so that your High Income Child Benefit Charge can be calculated.

What is an SA200?

The SA200 Short Tax Return is the shorter, simpler version of the SA100 Main Tax Return. You should only fill out and file an SA200 if HMRC tells you to or sends one to you.

What is a supplementary page?

Again, as the name suggests, supplementary pages are additional pages that you need to complete and file with your SA100 to report income and tax expenses linked to specific sources of taxable income. This enables HMRC to get a more detailed picture of your income and expenses from a specific income stream and work out how much tax you owe overall.

Each type of supplementary page has its own number, which corresponds to a different income source, as follows:  

• SA102 Used by employees or company directors 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 employment or directorship.
• SA103S Used to report income from self-employment if annual business turnover was below the VAT threshold for the tax year (£90,000 for the 2024-25 tax year). If it was above the VAT threshold, you need to use the SA103F. If you have more than one source of self-employed income, an SA103 must be used for each.
• SA104S Use this short version when filing your SA100 if you’re only reporting partnership trading income and interest or alternative finance receipts received after tax was deducted from banks or building societies. Otherwise use the SA104F to report full partnership income.
• SA105 Used to report rental income and other receipts from UK land and/or property or income from letting furnished holiday accommodation in the UK or EEA or premiums resulting from leasing out of land in the UK.
• SA106 Used to report foreign income or gains or to claim foreign tax credit relief.
• SA108 Used 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 purposes. People who are resident outside the UK but who earn UK rental property must file an SA109. It helps to ensure that they pay the correct amount of tax.

Need to know! Supplementary pages must be submitted with your SA100. The full list of supplementary pages can be viewed on GOV.UK.

What is an SA302?

You can get evidence of your earnings (an SA302) for the last four years 72 hours after you’ve filed your Self Assessment tax return. You can also get a tax year overview for any year. You might be asked for these as evidence of your income, for example, if you’re applying for a mortgage and you’re self-employed.

Need to know! If you’ve filed your Self Assessment tax return, you can print your own SA302 using HMRC’s online services or commercial tax return filing software.

Will HMRC send me a Self Assessment tax return?

HMRC will usually send you a tax return if you have untaxed income from investment, land or property, or income from overseas. You may also receive a Self Assessment tax return if you make capital gains above the annual exemption threshold (£3,000 in the 2024-25 tax year) or you were required to fill in a tax return last year.

Need to know! Do not rely on HMRC to tell you you need to submit a tax return if you know tax is payable on some or all of your income. Each year, you’re legally responsible for declaring all of your taxable income. If you receive a tax return, you must fill it in and file it, whether or not you owe any tax on your income.

When you use GoSimpleTax, you simply specify your sources of income and the necessary supplementary pages will automatically be included with your SA100. GoSimpleTax also makes it easier, quicker and cheaper to fill out and file your tax returns. Start your FREE trial to find out why so many other people like you love GoSimpleTax.   

Blog content is for information purposes and over time may become outdated, although we do strive to keep it current. It's written to help you understand your Tax's and is not to be relied upon as professional accounting, tax and legal advice due to differences in everyone's circumstances. For additional help please contact our support team or HMRC.