Our Self-Assessment tax return services

Completing your Self-Assessment tax return is an opportunity to claim a variety of exemptions and reliefs so that you only pay the tax you need to. To support you, our Tax team can: 

  • Complete and submit annual Self-Assessment tax returns 
  • Provide advice on Self-Assessment registration 
  • Tell you how much tax to pay and when 
  • Suggest ways you can reduce your personal tax liability 
  • Claim all allowable reliefs and deductions  

You may be able to claim for home office costs, professional subscriptions, travel mileage, accountancy fees, software tools and much more to offset your taxable income. 

We can also work through any concerns or worries you might have around past compliance. 

Do you need to complete a Self-Assessment tax return?

For most people who earn a small amount of savings interest and are either in full time employment or drawing a pension, their tax is calculated and deducted automatically – so there’s no need to complete a self-assessment. But there are exceptions.

Exceptions to this include:

  • You were self-employed as a sole trader and earned more than £1,000 (before taking off anything you can claim tax relief on) 
  • You were a partner in a business partnership 
  • You had a total taxable income of more than £150,000 
  • You had to pay Capital Gains Tax when you sold or ‘disposed of’ something that increased in value 
  • You had to pay the High-Income Child Benefit Charge 

You may also need to complete a Self-Assessment tax return if you have any untaxed income like: 

  • Money from renting out a property 
  • Tips and commission 
  • Income from savings, investments and dividends 
  • Foreign income 

If you make additional income by selling via online stores, or through side gigs alongside your main employment, you might also need to complete a Self-Assessment tax return. 

Self-assessment deadlines

The deadlines for self-assessment submission vary depending on the method you use for submission, but it’s important that you file before the deadline because the cost of penalties builds up quickly, and you’ll still incur a late filing penalty even if there’s no tax for you to pay. 

Online or paper tax return?

Tax returns can be filed online or on paper and you can use either method, although many find the convenience and speed of online submission to be helpful – as it gives them longer to complete their tax return.  

When using the online portal, some calculations are performed automatically for you, which reduces the opportunity for error, and before completing the submission, you’re given the option to download a PDF copy of all the completed forms, so you can cross check them with any paper records you might have – so there are few benefits to submitting on paper now. 

Submitting Your Tax Return on Paper:

  • The return must be filed by 31 October following the end of the tax year (eg 31 October 2025 for the tax year ending 5 April 2025).  
  • It is up to you to check that all the relevant sections have been completed. 
  • HMRC do not acknowledge receipt of paper returns, so you may want to send it by recorded delivery or obtain proof of posting in case there is a dispute over the late filing of the return. 
  • Penalties for late filing of a paper return run from 1 November following the end of the tax year (1 November 2025 for the tax year ending 5 April 2025). 

Submitting your Tax Return Online:

  • For online returns, the deadline is 31 January (31 January 2026 for the tax year ending 5 April 2025). 
  • The return preparation can be done using HMRC’s own software or by engaging an accountant or tax advisor.  
  • HMRC provide immediate acknowledgement that the return has been filed. 

Self-Assessment penalties

Missing the deadlines for submitting your self-assessment and/or paying any tax due result in some uncomfortable fines. 

If you are late in filing your tax return, you’ll get the following late filing penalties:  

  • an initial £100 penalty  
  • after 3 months, additional daily penalties of £10 per day, up to a maximum of £900  
  • after 6 months, a further penalty of 5% of the tax due or £300, whichever is greater  
  • after 12 months, another 5% or £300 charge, whichever is greater  

All partners will be charged a penalty if a partnership tax return is late. 

If you’re late in paying your tax, you’ll get penalties of 5% of the tax unpaid at:  

  • 30 days  
  • 6 months  
  • 12 months  

You’ll also be charged interest on the amount owed.  

For further information on penalties, visit gov.uk. 

When are my tax payments due under Self-Assessment?

Self-Assessment payments – which can include tax, Class 2 and 4 National Insurance contributions, and student loan repayments – are usually due by 31 January after the end of the tax year to which they relate. So, for example, any tax owed for the 2024/25 tax year would need to be paid by 31 January 2026. This is often known as the ‘balancing payment’. 

Payments on account

As well as a ‘balancing payment’ due for the previous tax year, some taxpayers also need to make instalment payments towards their annual self-assessment bill for the following year. These are called payments on account. 

Generally, if you need to make payments on account, you will need to make two payments, one on 31 July and another by 31 January in each tax year – but these do not include national insurance contributions (NICs) or any capital gains tax you might owe, so these will need to be calculated and paid for separately by the 31 January deadline. 

You normally have to make a payment on account if your previous year’s income tax bill (excluding class 2 NIC, if applicable) was over £1,000, unless more than 80% of your previous year’s income tax was taken off at source. 

Who we help

We provide tax advice to a variety of clients, from self-employed individuals to landlords, non-residents, partnerships, and High Net Worth clients. 

We can walk through your circumstances and show you the exemptions and claims you could be making use of to lower your tax bill while remaining tax compliant. 

If you have questions or concerns about Self-Assessment or another tax matter, please contact a member of our Tax team.