How to fill in supplementary Self Assessment forms if you're self-employed, a landlord or declaring capital gains

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If you have extra income to declare from self-employment, property or capital gains, you will need to fill in a supplementary page. If you’re:

  • self-employed you need to complete SA103
  • reporting property income, fill in SA105
  • declaring capital gains, complete SA108.

In these pages, you will need to report income from these sources which you’ve not paid tax on.

You will also get to declare any allowable expenses which will be deducted from your tax bill.

Self-employed (SA103)


If you’re earning money through self-employment, you will be asked to enter your turnover under the business income section.

This is the grand total of everything you had coming in during the tax year before expenses are deducted.

If you have more than one source of self-employed income, you can enter this amount separately, but make sure the job which you earn the most from is your main employment.


There are two ways to declare your expenses if you’re self-employed. You cannot claim expenses if you claim the £1,000 tax-free trading allowance.

If annual turnover is below £85,000 you can just enter your total expenses without having to itemise them. If you’re self-employed and your turnover is more than £85,000, you will have to enter an individual amount for each kind of expenses, plus a total at the end.

The different expenses you can include if you’re self-employed are:

  • cost of stock bought for resale
  • cost of equipment used at work
  • wages, salaries and other staff costs
  • payments to subcontractors (if you work in the construction industry)
  • vehicle and travel expenses
  • work building costs (including rent, power and insurance)
  • repairs and maintenance for work buildings and vehicles
  • office costs (including internet access, phones and stationery)
  • advertising and business entertainment costs
  • interest on loans
  • bank, credit card and other financial charges
  • accountancy, legal and other professional costs

You do not need to send in proof of your expenses, like receipts, when you submit your Self Assessment tax return. You will need to keep records of expenses for five years after you submit your return for that tax year in case HMRC ask you to produce them.

UK property income (SA105)


If you’re a landlord, you will be asked to enter the income from rented properties in two separate sections.

In the first section, you will need to enter the total income from all furnished holiday lettings in the UK. If you have any furnished holiday lettings in the European Economic Area (EEA), you will need to enter the total income from these on a separate page.

In the second section, enter the total rent and income from other properties.


You cannot claim expenses if you claim the £1,000 tax-free trading allowance.

If you make money from renting out a property you can claim expenses for:

  • rates, insurance and ground rent
  • property repairs and maintenance
  • loan interest and other financial costs
  • legal, management and other professional fees.

Capital Gains (SA108)


Income which you need to declare for Capital Gains Tax is called ‘disposal proceeds’.

You will need to fill in a separate ‘disposal proceeds’ total for residential property, non-residential property and shares and securities.

Expenses On a Capital Gains Tax return, you can claim for ‘allowable costs’. These include:

  • the price paid to buy the asset in the first place
  • costs of any improvements (must be reflected in the asset when it’s sold*)
  • other costs in buying or selling the asset (such as Stamp Duty when buying a property).

*What this means is, the improvement still needs to be present when the asset is sold. For example, you can’t claim for a new carpet in a house, if you remove the carpet before you sell the property.

It’s important to keep good records to make sure you don’t claim for the same thing twice. This is because you might be claiming expenses as part of your Self Assessment tax return for property in previous years.

For example, if you claimed for maintenance on a Buy to Let property in a previous tax year, you cannot claim for the same expense as part of your Capital Gains tax return when you come to sell the property.