How to file self assessment tax


Filing your self-assessment tax can be a daunting task, but with the right guidance and a clear understanding of the process, it can be a smooth and manageable endeavor. Self-assessment tax is the system used by many countries to collect income tax from individuals who have income from various sources, such as self-employment, investments, or rental properties. In this article, we will provide you with a step-by-step guide to help you navigate the self-assessment tax process efficiently.

Understand the Basics of Self-Assessment Tax

Before you start the process of filing your self-assessment tax, it’s essential to have a solid understanding of the basic concepts involved. Self-assessment tax requires you to declare your income, claim any applicable tax reliefs or allowances, and calculate the amount of tax you owe. You will typically need to file a self-assessment tax return annually by a specific deadline.

Gather Necessary Documents

To complete your self-assessment tax return accurately, you will need several documents and pieces of information. These include:

Personal information: 

Your National Insurance number, UTR (Unique Taxpayer Reference) if you have one, and your contact details.

Income information:

 Gather details of all your income sources, such as employment income, self-employment income, rental income, dividends, interest, and any other sources of income.


 Keep records of all allowable expenses related to your income sources, including receipts, invoices, and bank statements.

P60 or P45:

 If you have been employed during the tax year, you will receive a P60 from your employer, summarizing your earnings and tax paid. If you left your job, you may have a P45.

Statements of savings and investments:

 Collect information on your savings accounts, investments, and any capital gains.

Pension contributions:

 If you contribute to a pension scheme, make sure to have records of your contributions.

Register for Self-Assessment

If you have never filed a self-assessment tax return before, you will need to register for self-assessment with your country’s tax authority. In the UK, for instance, you can register for self-assessment online by visiting the HM Revenue & Customs (HMRC) website. You will receive a Unique Taxpayer Reference (UTR) once your registration is complete.

Choose Your Filing Method

You have several options for filing your self-assessment tax return, depending on your country’s tax authority. The most common methods include:


Filing your return online is often the quickest and most convenient method. You can do this through the official website of your country’s tax authority.


Some tax authorities still allow paper tax returns, but this method usually comes with earlier deadlines and more time-consuming processing.

Using Software:

 You can also use approved tax software to file your return, which can make the process more straightforward and help you calculate your tax liability accurately.

Keep Track of Deadlines

Knowing the deadlines for filing your self-assessment tax return is crucial to avoid penalties and interest charges. These deadlines can vary by country and may also depend on how you choose to file your return. Typically, self-assessment tax returns are due by the end of the tax year, with additional time for online filing.

Fill Out the Tax Return

When filling out your self-assessment tax return, make sure to provide accurate and complete information. You’ll need to enter details about your income, expenses, and any other relevant financial information. Some of the key sections of the tax return include:

Personal information: 

Fill in your name, address, National Insurance number, and UTR if applicable.

Income: Report all sources of income, including employment, self-employment, rental income, and any other income streams. Ensure that you include all relevant forms and documents.


 Deduct allowable expenses from your income to calculate your taxable profit or income.

Tax reliefs and allowances:

 Claim any tax reliefs and allowances you are eligible for, such as the personal allowance or business-related expenses.

Additional information:

 Some tax returns may require additional information, such as details about foreign income or capital gains.

Calculate Your Tax Liability

Once you have filled in all the necessary sections of your tax return, you can use the provided tools or tax software to calculate your tax liability. Be sure to take into account any applicable tax reliefs and allowances to minimize your tax liability legally.

Pay Any Tax Owed

After calculating your tax liability, it’s essential to pay any tax owed promptly. Your country’s tax authority will provide various payment methods, such as bank transfer, debit or credit card payments, or setting up a direct debit. Failing to pay your tax on time may result in penalties and interest charges.

Submit Your Tax Return

Once you have filled out your self-assessment tax return and paid any tax owed, submit it to your country’s tax authority by the deadline. If you’re filing online, make sure to save a copy of your submission confirmation for your records.

Keep Records

It’s crucial to keep records of your self-assessment tax return, including all supporting documents, for a specified period. In the event of an audit or inquiry, having well-organized records will help you provide the necessary evidence to support your tax return.

Seek Professional Advice if Necessary

Filing a self-assessment tax return can become complex, especially if you have multiple sources of income or specific tax situations. In such cases, seeking professional advice from a qualified tax accountant or advisor can be valuable. They can help you navigate the process, ensure that you’re maximizing your tax reliefs, and reduce the risk of errors or omissions on your return.


Filing a self-assessment tax return may seem like a daunting task, but with the right information and preparation with the help of personal tax accountant, it can be a manageable and even straightforward process. Understanding the basics, gathering necessary documents, meeting deadlines, and using the right filing method are all critical steps in the process. Remember to calculate your tax liability accurately, pay any taxes owed on time, and maintain comprehensive records. If you have complex tax situations, don’t hesitate to seek professional advice to ensure compliance with tax laws and regulations. By following these steps, you can navigate the self-assessment tax process with confidence and ensure that you fulfill your tax obligations effectively.

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