Filing your first self-assessment tax return can feel overwhelming, but it doesn’t have to be. Whether you're a freelancer, landlord, or small business owner, understanding the process helps avoid costly mistakes and HMRC penalties. 

At East London Accountants, we help clients across London and the UK navigate self-assessment with confidence. This guide breaks down the essentials so you can file correctly and on time. 

Who Needs to File a Self-Assessment Tax Return? 

You need to file a return if in the last tax year (6 April to 5 April) you: 

• Were self-employed or a sole trader 
• Earned over £1,000 from a side hustle or freelance work 
• Received untaxed income (e.g. rental income, dividends, crypto) 
• Were a company director 
• Claimed Child Benefit and earned over £50,000 
• Received income from abroad 
• Had income over £100,000 

If you’re unsure, it’s best to check with an accountant. 

Step 1: Register for Self-Assessment 

Before filing, you must register with HMRC. The deadlines are: 

• 5 October after the end of the tax year you started trading 

Register as: 

• A sole trader (self-employed) 
• Not self-employed (e.g. landlord, investor) 

HMRC will send you a Unique Taxpayer Reference (UTR) number and set up your online account. 

Step 2: Prepare Your Financial Records 

Gather all relevant documents, including: 

• Income invoices 
• Bank statements 
• Business expenses and receipts 
• Pension contributions 
• Interest from savings 
• Dividend statements 
• Rental property income and costs 
• Student loan details 

Use software like Xero or QuickBooks to track this throughout the year. 

Step 3: Log in and Complete the Online Return 

Log in to HMRC’s online portal using your Government Gateway ID. You’ll be guided through sections relevant to your income sources. 

You’ll need to declare: 

• Total income 
• Allowable expenses 
• Tax reliefs (e.g. pension contributions) 
• Capital gains (if any) 

Step 4: Submit and Pay 

The key deadlines are: 

• 31 January – Online return and tax payment due 
• 31 July – Second payment on account (if applicable) 

Payment can be made by: 

• Direct Debit 
• Bank transfer 
• Debit or credit card 

Late submissions or payments result in penalties, starting at £100. 

Tips for a Smooth First Return 

• Start early to avoid last-minute stress 
• Use digital software to organise records 
• Keep all receipts and documentation for at least 5 years 
• Double-check figures before submitting 

How East London Accountants Can Help 

We offer complete self-assessment support for: 

• Sole traders and freelancers 
• Landlords with rental income 
• Investors and directors 
• Crypto and dividend earners 

Our service includes: 

• Registration with HMRC 
• Income and expense review 
• Full return preparation and submission 
• Advice on allowable deductions 
• Year-round support 

With over 20 years of experience, we help you stay compliant while keeping your tax bill as low as legally possible. 

Book a Free Self-Assessment Consultation 

Filing your first tax return? Get in touch with East London Accountants today. We’ll simplify the process, ensure you don’t miss any deductions, and handle HMRC submissions on your behalf.