As part of your Income Tax Self Assessment submission, it’s essential to make sure that you submit the correct forms (“supplementary pages”) corresponding to your income streams.

At first glance, perhaps the most confusing part is deciding between filling in the “short” or “full” forms for self-employment – or maybe even both?

In today’s article, we run through the essentials regarding Self Assessment tax returns and explain the difference between the two self-employment tax form variants: “short” (SA103S) vs. “full” (SA103F).

Income Tax Self Assessment: overview (self-employment)

If you’re self-employed (i.e. a sole trader), then there is a decent likelihood that you will be required to submit a Self Assessment tax return this year.

Depending on various thresholds and allowances, you might not actually need to pay tax on your income. However, if you earn more than £1,000 in a tax year, you are expected to file Self Assessment anyway to declare this income.

Self Assessment tax return vs. PAYE

In traditional (contractual) employment, your employer typically deducts Income Tax through PAYE (Pay As You Earn). This means that your Income Tax is calculated and paid on your behalf before you receive your take-home pay.

As a self-employed business owner, however, you are trading as yourself (rather than through a registered, limited company as an employee). Therefore, self-employment income is regarded as a type of personal income which must be declared via Self Assessment.

ITSA supplementary forms

Income Tax Self Assessment covers taxation across a wide range of personal income streams – not just self-employment earnings. For instance, property income (as a landlord), or income generated through capital gains or investments (such as dividends) must also be considered when filing your tax return.

Therefore, since Self Assessment takes into account so many types of income, each tax return must be tailored to your specific circumstances. In order to achieve this, it is essential that you understand which supplementary pages apply to you – and which don't.

Self-employment (short) vs. Self-employment (full)?

Self-employment can be declared through two different Self Assessment supplementary pages: short (SA103S) or full (SA103F). Depending on the specifics of your self-employment income – assuming that it reaches at least £1,000 – you will need to fill in and submit one of these (but not both).

You should complete the “Self-employment (full)” pages if any of the following circumstances apply:

  • Your turnover reached £85,000 (or would have done so if you’d traded for a whole year)
  • You are claiming Overlap Relief (or have unused Overlap Relief you need to use)
  • Your taxable period of self-employment (“basis period”) differs from your accounting period, and you are affected by basis period reform. (For more information, refer to HMRC’s page: How to calculate your taxable profits.)
  • You have adjustment income due to changing your accounting basis
  • You need to adjust profits subject to Class 4 National Insurance contributions (NICs)
  • You were included in the Managing Serious Defaulters (MSD) programme for the given tax year

If none of the points above applies, you should submit the “Self-employment (short)” pages (source) – assuming your self-employment reaches the £1,000 threshold.

How to file your Self Assessment

Arguably the simplest way to file your Self Assessment is through a dedicated online tax service such as AbraTax. This way, you simply fill in the form provided and it automatically works out which supplementary pages you need.

Once you have finished entering the details required, AbraTax will calculate your tax due and file your Self Assessment directly with HMRC. You will also receive instant confirmation and a receipt ID as proof.

Best of all, this service is currently completely free! Since Making Tax Digital will soon make filing ITSA online mandatory, why not sign up and get ahead of the curve today?

TL;DR

  • "Self-employment (full)" is required if turnover reaches the VAT threshold (£85,000).
  • You might also need “Self-employment (full)” under some complex circumstances (e.g. accounting date issues or MSD monitoring due to prior tax evasion).
  • Online services such as AbraTax select the correct forms automatically.
Disclaimer: We aim to offer educational articles on our blog, focusing on tax-related topics. However, it's important to note that over time, the relevancy of this content might diminish, and we cannot guarantee accuracy. While these articles serve as a tool for enhancing tax knowledge, they are not a replacement for expert advice in accounting, taxation, or legal matters, given the unique nature of each individual's situation. Should you require personalized assistance, we encourage contacting HM Revenue and Customs (HMRC).