Self-Assessment Tax Returns
Filing your Self-Assessment Tax Returns can be a daunting task, especially with the complexities of the UK tax system. Our team of expert self-assessment accountants is here to help you navigate the process, ensuring compliance and minimising your tax liabilities.

What is Self-Assessment?
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Tax Liability Calculation
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Frequently Asked Questions
What is a Self-Assessment tax return?
A Self-Assessment tax return is a way for individuals, including self-employed people, company directors, and those with complex financial affairs, to report their income, expenses, and other financial details to HM Revenue & Customs (HMRC). It helps HMRC calculate how much tax you owe.
Who needs to file a Self-Assessment tax return?
You need to file a Self-Assessment tax return if you:
- Are self-employed or a business partner
- Are a company director (unless it’s a non-profit-making company)
- Earn income from property or foreign sources
- Have income over £100,000
- Receive significant untaxed income (e.g., from savings, investments, or freelance work)
- Claim certain tax reliefs or allowances (e.g., Marriage Allowance, Blind Person’s Allowance)
What is the deadline for submitting a Self-Assessment tax return?
- Paper returns: Must be filed by 31st October following the end of the tax year (5 April).
- Online returns: Must be filed by 31st January following the end of the tax year. For example, for the 2023/24 tax year (ending 5 April 2024), paper returns must be filed by 31 October 2024, and online returns by 31 January 2025.
What happens if I miss the Self-Assessment deadline?
If you miss the deadline, you’ll face penalties:
- £100 penalty if your return is up to 3 months late.
- Additional penalties of £10 per day after 3 months.
- After 6 months, a further penalty of £300 or 5% of the tax due (whichever is higher).
- After 12 months, an additional penalty may apply, which can be up to 100% of the tax owed.
Can I claim expenses on my Self-Assessment tax return?
Yes, if you're self-employed, you can claim a variety of business-related expenses to reduce your taxable income. Common expenses include:
- Office supplies and equipment
- Travel and vehicle costs
- Utilities and phone bills (for work-related use)
- Professional fees (e.g., accountants, legal fees)
- Home office costs (if applicable) Make sure to keep accurate records and receipts for all expenses.
What are the key tax changes for the 2023/24 tax year?
Some key changes for the 2023/24 tax year include:
- The Income Tax Personal Allowance remains at £12,570, but some higher earners (over £100,000) may see their allowance tapered.
- The High Income Child Benefit Charge still applies for those with income over £50,000, reducing the Child Benefit amount. From 6 April 2024, the threshold has increased from £50,000 to £60,000
- National Insurance Contributions the rate of employers' NIC will rise to 15% from the current 13.8%.
- Capital gain tax: CGT rates have been increased including increasing the lower rate of CGT from 10% to 18% and the higher rate from 20% to 24%, with effect from 30 October 2024.
What if I’m not self-employed but still need to file?
You may need to file a Self-Assessment if you receive untaxed income from sources such as:
- Rental income from property
- Investment income (e.g., dividends, interest)
- Capital gains (from selling assets such as stocks, property, etc.)
- Foreign income or pensions You will also need to file if you want to claim specific tax reliefs, like Marriage Allowance or Blind Person’s Allowance.
How do I file a Self-Assessment tax return?
You can file your Self-Assessment tax return online through the HMRC website. If you’re filing for the first time, you need to register with HMRC and create an account. Alternatively, you can file a paper return, but this is less common and slower.
Can I pay my Self-Assessment tax bill in instalments?
Yes, if your tax liability is over £1,000 and your total tax due is more than 80% of your income, you can apply to pay your tax in instalments through a Time to Pay arrangement with HMRC. You can arrange this through your online account or by contacting HMRC directly.
What if I make a mistake on my Self-Assessment tax return?
If you make a mistake after submitting your Self-Assessment return, you can amend it online through your HMRC account, provided it's within 12 months of the original filing deadline. If it's more than a year, you may need to request a correction through HMRC’s customer service.
How do I know if I need to make payments on account?
If your tax bill is over £1,000 and you haven’t had enough tax deducted at source (e.g., through PAYE), you may need to make payments on account. These are advance payments towards your next tax bill, due in two instalments: 31st January and 31st July.
Can I claim tax relief for working from home?
Yes, if you work from home, you can claim a proportion of your household expenses as tax-deductible, including:
- Utility bills (gas, electricity, water)
- Broadband and telephone costs
- Rent or mortgage interest (for the proportion of your home used for work) You can use a flat rate of £6 per week or calculate actual costs, depending on which works out best for your circumstances.
What if I’m a sole trader and don’t have any income this year?
If you’re a sole trader and had no income or profit for the year, you still need to submit a Self-Assessment return. However, you won’t need to pay any tax if your earnings were below the personal allowance, and you’ll avoid penalties as long as your return is filed on time.