Can I do my own self assessment?
Overview
You can complete your own Self Assessment tax return and HMRC’s online portal makes this simple. This guide explains what Self Assessment is, when filing your own return is advised, and the thresholds beyond which professional support is beneficial. You’ll learn the practical steps for submission as well as what documentation you’ll need. The guide concludes with answers to relevant common questions.
For broader guidance on whether to hire support with your finances, see our guide Do I Need an Accountant?
What is Self Assessment?
“Self Assessment” is the system HM Revenue and Customs (HMRC) uses to collect Income Tax in the UK. The process involves submitting a Self Assessment Tax Return detailing all taxable income so HMRC can calculate any tax due that was not collected through PAYE.
The return is submitted annually, covering income from the previous cycle (a cycle runs from 6 April to 5 April). Tax returns are usually due by 31 January following the end of the tax year.
Who it applies to
Founders
Individuals who class themselves as self-employed or sole traders
Directors
Company directors who receive dividends or untaxed income
Landlords & Investors
Individuals with rental income, capital gains or investment returns
When to file your own return
HMRC’s online system is designed for individuals to complete and submit returns themselves, and many taxpayers do. If you’re self-employed with a turnover under £85k, your Self Assessment will only contain two figures: total business income and total business cost. In scenarios like this, self-submission is encouraged.
As a rule of thumb, self-employed single-owner businesses, such as freelancers, creatives, web designers and consultants should consider filing their own tax returns.
How to file a return
Filing a return can be broken down into two phases: gathering the required documentation and submitting the relevant forms through HMRC’s online portal. The next two sections give practical guidance for each phase.
Information to prepare
You’ll need to prepare documentation detailing: salary or wage income; rental income; business profit; interest earned (initial £1000 is tax-free); dividends received (initial £2000 is tax-free); and business expenses and costs. If you don’t already use an accountant, it helps to store monthly records of this information to avoid issues as the submission deadline approaches.
Relevant forms
When to seek professional support
There are certain thresholds beyond which professional support with your self assessment return can save time and reduce risk. You should consider seeking support if:
You have multiple sources of income
You receive income from more than one source, e.g. employment, entrepreneurship, rents or investments. Each source has its own reporting complexity.
You receive income from rental property
You earn income from one or more properties. Property-related tax rules frequently change and can be difficult to understand and apply correctly.
You receive dividends or investment income
You receive income from shares, funds, savings or investment disposals. Dividend allowances, capital gains rules and investment reporting add complexity to your return.
You run a limited company
You are a company director and receive income through salary, dividends or benefits. Company and personal tax obligations overlap, which makes accurate reporting more technical.
You receive income from overseas
You receive income from overseas employment, investments, property or pensions. International tax rules and double taxation relief can be challenging to navigate.
You have complex expenses
You regularly claim business expenses or operate from home. Determining what is allowable can be difficult without tax knowledge.
Common questions
In some cases, yes. HMRC may charge penalties and interest if a tax return is submitted late, contains careless inaccuracies, or results in underpaid tax.
Filing directly through HMRC’s online Self Assessment system is free. However, most founders need bookkeeping software, which incurs subscription costs.
For Self Assessment returns, we charge a flat fee of £300.
As a rule of thumb, support is often worthwhile if you have multiple income streams, rental income, dividends, capital gains, foreign income or limited company involvement. See the previous section for more detail.