All You Need To Know About Filing Your Self Assessment Tax Return

Filing a self assessment tax return is an important process that must be done accurately to ensure that you are paying the correct amount of taxes. HMRC guidelines and policies can be complex and difficult to understand, which is why it’s important to have all the information you need before you start filing your tax returns. 

This blog will provide an overview of HMRC guidelines and policies for self assessment tax returns, as well as tips to ensure you are filing your tax returns correctly.

Overview of HMRC Guidelines & Policies for Self Assessment Tax Return

The HM Revenue & Customs (HMRC) is the government agency responsible for managing taxes in the UK. The HMRC tax return has guidelines and policies for both individuals and businesses to ensure they are compliant with all legal requirements and paying their taxes correctly. 

When it comes to tax return self assessment, there are certain conditions that must be met to ensure compliance. 

Those who must submit a self assessment tax return include any individual with income over £50,000 or have savings and investments, are in a partnership business, self-employed or have rental income. 

To complete your self assessment tax return accurately, you need to understand the different types of income and expenses that can be reported on your tax return. 

Types of Income that are Taxable Under Self Assessment

The HMRC tax return guidelines specify that all income should be reported in your self assessment tax return. This covers any taxable income, such as wages from employment, interest on savings and investments, profits from your business, or rental income. Any pension payments received are also liable for taxation and must be declared on your tax return. 

The following are the different types of income that are taxable under self assessment:

  • Wages earned from employment:
  • Interest in savings and investments:
  • Profits from business ventures
  • Rental incomes 
  • Pension payments 
  • Dividends from shares in a company.

These are the different types of income that are taxable under self assessment and must be reported on your tax returns.

Types of Expenses That Are Deductible Under Self Assessment

The HMRC also allows for certain expenses to be deducted from your taxable income. These deductions are intended to reduce the amount of tax you pay and should only be declared if they are related to your work or business activity. 

The following are some of the different types of expenses that can be deductible under self assessment: 

Travel expenses

This covers any costs incurred when traveling to work, such as public transport fares or fuel for your car. 

Home office expenses

If you work from home, you can claim a portion of your household bills, such as broadband and utilities, as tax-deductible business expenses. 

Business equipment

You can claim the cost of any business-related equipment, such as computers or phones, purchased for use in your work. 

Professional fees

If you have paid for any professional advice or services related to your business, such as accountancy fees, you can claim these costs as deductible expenses. 

Advertising and marketing costs

Any marketing or advertising costs incurred for the purpose of promoting your business are also deductible expenses. 

Insurance premiums

Any insurance premiums paid for business-related cover are also allowable deductions from your taxable income. 

Subscriptions to professional organisations

If you have paid any fees to professional organisations related to your work, these can be deducted from your taxable income.

How to Claim Tax Relief on Your Expenses

In the United Kingdom, Self Assessment tax return can be a complex process. One way to reduce your tax bill is by claiming tax relief on certain expenses that you incur for your business or investments. You can claim these deductions from HMRC (Her Majesty’s Revenue and Customs) when completing your Self Assessment tax return. 

The rules for claiming relief on expenses can seem complex, but HMRC has published guidance to help you understand what is and isn’t allowed. 

  • The deduction must be incurred ‘wholly and exclusively for the purpose of your business or investments: if it’s partly used for private benefit, you won’t be able to deduct the full amount.
  • You need to keep records of all costs that you are claiming, such as receipts, invoices, and bank statements.
  • Don’t forget any capital allowances on assets (such as computer equipment) that you may have bought in your business. 
  • You can’t claim anything back that was reimbursed by HMRC or anyone else. 

When it comes to filing your Self Assessment tax return, you need to enter all of the expenses that you have incurred in the relevant sections. HMRC self assessment tax return outlines which section should be used depending on what type of expense it is.

How to Use the HMRC Self Assessment Calculator

For help in calculating your Self Assessment tax return, HMRC provides a calculator that you can use. To get an accurate figure of what you owe, make sure to provide all relevant information into the calculator, including: 

  • Your profits or losses from self-employment, rental income, and/or other sources of income 
  • Any capital  gains you have made 
  • Any tax reliefs and allowances that are available to you
  • Any student loan deductions and/or state pension payments you have made 

Once all of the information is entered, it will calculate an estimated figure for what your tax bill should be. You can then use this as a guideline when completing your Self Assessment tax return.

Latest Changes to Self Assessment

Since the introduction of Making Tax Digital, HMRC has been making improvements to the way in which self assessment returns are processed.  Through Pay Self Assessment Tax by HMRC, it’s now easier than ever before to file your tax return online: you can do it 24/7, pay any taxes due electronically, and even make use of digital tools to help with budgeting and forecasting.

Making sure you are aware of the latest changes and keeping up to date with HMRC guidelines for self assessment tax returns is essential if you want to stay compliant, so here we’ve put together a guide to help make things easier. 

Following are the HMRC guidelines and policies you should be aware of when filing your self assessment tax return:

Deadlines: The deadline for submitting your self assessment tax return is 31st January each year (31st October if you’re submitting a paper return). If you fail to meet this deadline, you may be subject to penalties and interest.

Making Tax Digital: All self assessment returns now must be filed online, and if you’re a VAT registered business, you must also use the MTD system.

Online Submissions: You can submit your tax return 24/7 through HMRC’s secure website or through an authorised tax agent.

Tax Payments: You can pay any taxes due electronically through the HMRC website or by cheque, debit/credit card, or direct debit. It’s important to note that you’ll also need to ensure your bank account details are up to date in order for payments to be processed correctly. 

Tips for Filling Your Self Assessment Tax Return On Time and Accurately

Keep accurate records: 

Make sure you keep accurate and up-to-date records of your income from all sources, including bank statements, payslips, and receipts.  This will make it much easier when it comes to filing your return.

File early:

Filing your tax return early will reduce the chances of making any mistakes and also allows you to plan ahead for any payments that need to be made. 

Use digital tools:

HMRC offers a range of digital tools to help with budgeting, forecasting, and submitting your return. These can be extremely useful and make the process much easier. 

Keep track of deadlines: 

Make sure you’re aware of the deadlines for filing and paying your return and any other important dates throughout the process. 

Use authorised agents: 

If you’re struggling to fill in your tax return, or don’t have time to do it yourself, then you can use an authorised agent such as a chartered accountant or tax advisor. They’ll be able to help you file your return and keep up to date with any changes in the law. 

Common Mistakes To Avoid When Filing Your Self Assessment Tax Return

Not filing on time: This is the most common mistake made when submitting self assessment returns. Make sure you’re aware of the deadlines and do everything you can to submit your return on time to avoid any penalties or interest. 

Failing to declare all income: Make sure that you include every source of income in your return; otherwise, you could face a penalty. 

Not understanding the rules: If you’re unsure about any of the HMRC rules or regulations, make sure you seek advice from an expert or authorised agent before submitting your return. 

Inputting incorrect information: Double-check that all of the information you’ve entered into your return is correct before submitting it, as any incorrect information could result in additional charges or even an investigation. 

Overlooking deductions: Make sure you take advantage of all the deductions that are available to you and don’t miss out on any potential savings. 


Filing your self assessment tax return can be a daunting task, but by following the HMRC guidelines and policies, you can make sure that everything is done correctly and on time. Make sure to take advantage of any digital tools available to you, as well as expert advice if needed, and keep track of all relevant deadlines. 

Avoiding common mistakes such as not filing on time, failing to declare all income, and inputting incorrect information is also important in order to avoid any unexpected penalties or interest.  By following this guide from Evirtual Accountants, you can be sure that your tax return is accurate and submitted on time.

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