Millions of individuals and businesses are required to complete and file a self-assessment tax return to HMRC to report their income and calculate their tax liabilities. Our latest article provides an overview of how to complete a self-assessment tax return, the documents you need to submit a tax return and the filing deadline.
What is a self-assessment tax return?
Self-assessment is a system HM Revenue and Customs (HMRC) uses to collect Income Tax. Tax is usually deducted automatically from pensions and wages, but people and businesses with other incomes must report it in a tax return. If you need to send a tax return, you must complete it after the end of the tax year (5th April) it applies to and submit it by the 31st January deadline.
If you are unsure whether you need to complete a self-assessment tax return, you can check on the government’s website. Our recent article also has useful information to help you determine if you need to file a tax return.
Do you need to set up an account to submit a tax return?
If this is your first time submitting a tax return, you must register for self-assessment by the 5th of October. Once you’ve registered, you’ll be sent your Unique Taxpayer Reference (UTR).
You must set up a Government Gateway account to submit your self-assessment online. To do this, follow the instructions in the letter containing your UTR.
Once you’ve set up the account, you’ll receive an activation code in the post, which you will need to complete the setup of your Gateway account.
If you’ve submitted a tax return before, you’ll need your old UTR to register and set up the account.
How do you complete a self-assessment tax return?
Before you file your self-assessment, you need to have the following documents:
- Your National Insurance number
- Your ten-digit Unique Taxpayer Reference (UTR)
- Records of any expenses relating to self-employment
- Details of your untaxed income from the tax year, including income from self-employment, dividends and interest
- P60 or other records showing how much income you received that you’ve already paid tax on
- Any contributions to charity or pensions that might be eligible for tax relief
When you submit your tax return online, you only need to fill out the sections that apply to you. There are two sections to the tax return. The main section is the SA100, which deals with:
- Pension contributions
- Taxed and untaxed income in the form of interest and dividends
- Benefits including, Child Benefit, State Pension, and Blind Person’s Allowance
- Charitable donations
You may need to complete supplementary pages if you have income to declare income from self-employment, as a company director, income from abroad, income as a foreign national (or dual resident), or have to declare Capital Gains.
You only need to complete an SA200 tax return if HMRC sends it to you.
Get help with your tax return
If you need help with completing and submitting your self-assessment tax return, you can:
- Appoint someone to fill in and send your tax return, for example, an accountant
- Ask HMRC’s digital assistant
- Get technical help with your online account
- Watch videos and join webinars
- Contact HMRC for general self-assessment enquiries
What is the deadline for submitting a self-assessment tax return?
The deadline for submitting an online self-assessment tax return is the 31st of January. You can expect a fine of £100 if your tax return is up to three months late or if you pay your tax bill late. You will have to pay more if it is later, and HMRC will charge interest on late payments. However, you can appeal against a penalty if you have a reasonable excuse. Beyond three months, there is a more complex system of fines based on daily penalties and so-called tax gear penalties. You can use HMRC’s penalty estimation tool to see how much you could be fined for late submissions or payments.
The Self-Assessment Hub has lots of useful articles to help you understand tax returns
If you are required to submit a self-assessment tax return for the first time, it can seem like a daunting experience. However, don’t worry – the Self-Assessment Hub website has lots of useful guides and articles that will help you understand your tax return requirements and file a tax return accurately.
The government’s website also has lots of useful videos, articles and tools to help you understand your filing requirements. Here are some useful articles on our website that you may find helpful:
- Mastering self-assessment tax returns: Your guide to accurate tax calculations and financial planning
- A comprehensive guide to registering for self-assessment in the UK
- Advantages and disadvantages of hiring an accountant to assist with your self-assessment tax return
- A guide to calculating how much tax you owe via your self-assessment tax return
- Self-assessment tax return: Understanding payment deadlines and penalties
