Register for Self-Assessment

How to Register for Self-Assessment: A Step-by-Step Guide

Running a successful business means not only serving customers but also managing finances, including fulfilling tax obligations. For restaurant or bar owners, IT professionals, construction managers, and any adult citizens earning income outside traditional PAYE systems, registering for Self-Assessment is crucial. Whether you’re a sole trader or a partner in a business, our guide will help you through the self assessment step-by-step registration process, help you avoid common mistakes, and explain how to register online or by post and what to do after registration.

What is Self-Assessment

Self-Assessment is an HMRC system for collecting Income Tax, where individuals report their income and calculate their tax liability. This is essential for the self-employed, company directors, or anyone with additional income.

Why You Need to Register for Self-Assessment

Registering for Self-Assessment is essential for several reasons:

  • Legal Obligation: If you earn income outside the traditional PAYE system, it is a legal requirement to report your income to the tax authorities. Failing to register and submit your tax returns can result in penalties and interest on any unpaid tax.
  • Accurate Tax Reporting: Registering for self-assessment ensures that all your income sources are reported accurately. This includes income from business activities, rental properties, investments, or any other non-PAYE sources.
  • Maximize Deductions: By completing a self-assessment, you can claim allowable expenses and deductions that might reduce your tax liability. This could include business expenses, pension contributions, and other deductible expenses related to your income sources.
  • Financial Planning: Understanding your tax obligations can help you with better financial planning. Knowing how much tax you need to pay and when can help you manage your cash flow more effectively.
  • Avoid Penalties: Timely registration and filing of your self-assessment are crucial to avoid late filing penalties and interest charges. Meeting all deadlines is essential to prevent additional costs.
  • Credibility and Compliance: Being compliant with tax laws enhances your credibility. This is particularly important if you plan to apply for loans or investment opportunities, as financial institutions often look at your tax compliance history.

Step-by-Step Guide to Registering for Self-Assessment

Registering for Self-Assessment is essential for anyone who earns income outside the traditional PAYE system, such as the self-employed, company directors, and those with additional untaxed income. Follow these steps to ensure you complete the process correctly and efficiently.

Register for Self-Assessment as a Self-Employed Person

1. Set up a Government Gateway Account: Visit the HMRC website and make a Government Gateway user ID and password. If you already have a business tax account, sign in with your existing credentials.

2. Answer Preliminary Questions: Specify that you want to register for Self-Assessment by answering a few initial questions.

3. Fill in the Online Registration Form: Provide details about yourself and your business:

    • Your name (and any previous name)
    • National Insurance number
    • Date of birth
    • Home address
    • Telephone number and email address
    • The reason you need to register
    • Business name
    • Business address (if different from your home address
    • The date you started self-employment

4. Watch HMRC’s Guidance Video:
HMRC provides a helpful video tutorial on registering for Self-Assessment.

5. Receive Your UTR and Activation Code:

    • Within 1-2 weeks, you’ll receive your Unique Taxpayer Reference (UTR) and an activation code by post.
    • Use these credentials to sign in and activate your Self-Assessment service within 28 days.

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Register for Self-Assessment as a Company Director and Shareholder

1. Create a Government Gateway Account: Follow the same steps as above to create or sign in to your Government Gateway account.

2.Visit the Online Registration Form: Go to and sign in to your tax account.

3. Fill in the Registration Form: Provide the following information:

  • Your full name (and any previous name)
  • National Insurance number
  • Date of birth
  • Your personal UTR (if you already have one)
  • Residential address and the date you moved there
  • Telephone number and email address
  • The reason for registering (e.g., ‘I am a company director’)
  • Date you received untaxed income

4.Watch HMRC’s Guidance Video: If you are still having trouble filling out the application, HMRC offers a video tutorial specifically for directors and shareholders.

5. Receive Your UTR and Activation Code: As with self-employed individuals, you’ll receive your UTR and activation code by post within 1-2 weeks. Use these to activate your online account within 28 days.

Registering for Self-Assessment by Post

If you’re unable to register online or fall into specific categories such as receiving income from UK land and property, taxable foreign income, or having Capital Gains Tax, you may need to register by post. Complete the SA1 form online, print it, sign it, and post it to:

  • HM Revenue and Custom
  • NIC&EO
  • BX9 1AN

Most Common Mistakes to Avoid for Self-Assessment

Filing a Self-Assessment tax return can be straightforward, but many people encounter common pitfalls. Here are the mistakes to avoid to ensure a smooth process and prevent unnecessary penalties.

  • Missing Deadlines: Ensure you register before 5 October following the end of the tax year for which you’re reporting.
  • Incorrect Information: Double-check all personal and business details before submitting the form.
  • Not Activating Online Account: Activate your account within 28 days of receiving your activation code.
  • Ignoring Notifications: Keep an eye on communications from HMRC to avoid missing important updates.

What to Do After Registration for Self-Assessment

After successfully registering for Self-Assessment, follow these steps to ensure you stay compliant and manage your tax responsibilities effectively.

  • Keep Records: Maintain detailed records of all income and expenses for accurate reporting
  • File Your Tax Return: Submit your Self-Assessment tax return by the deadlines—31 October for paper returns and 31 January for online returns.
  • Pay Your Taxes: Ensure timely payment of any taxes due to avoid penalties and interest charges.
  • Consider Professional Help if Needed: Don’t forget to consider hiring an accountant, especially if your accounts are complex.


Registering for Self-Assessment is a vital step for anyone earning untaxed income. By following this article, you can ensure smooth registration and compliance with HMRC’s requirements, allowing you to focus on growing your business.

Frequently Asked Questions

No, you can file your return yourself using HMRC’s online service. However, if your accounts are complex, consulting an accountant is advisable.

You must register by 5 October after the end of the relevant tax year. For the 2024/25 tax year, the deadline is 5 October 2025.

You will pay income tax on earnings above the Personal Allowance and may also need to pay National Insurance contributions.

Yes, if you receive income from UK land, property, or other specific circumstances, you may need to register by post using form SA1.

Yes, most people can register online. If you can’t, you can register by post.

Missing the deadline can result in penalties and interest charges. Register as soon as possible to avoid these.

HMRC needs to know your total income, any employment benefits, foreign income, pension income, and earnings from property. Detailed records of your income and expenses should be maintained for accurate reporting.

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