Self Assessment Tax Return: A Complete Guide for First-Time Filers

Navigating the world of taxes can feel overwhelming, especially if it's your first time. If you’re self-employed, a freelancer, a landlord, or have income that isn’t taxed at source, you’re likely required to file a Self Assessment Tax Return. This comprehensive guide by Stewart Accounting will walk you through everything you need to know to confidently complete your Tax Return Self Assessment and avoid common pitfalls.

What is a Self Assessment Tax Return?

A Self Assessment Tax Return is a system used by HM Revenue and Customs (HMRC) to collect income tax. While most individuals have taxes deducted automatically from their wages, pensions, or savings, others need to report their income directly to HMRC. This is typically the case for people who earn income outside of PAYE (Pay As You Earn) systems.

You are required to submit a Self Assessment Tax Return if you:

Are self-employed as a sole trader and earned more than £1,000
Are a partner in a business partnership
Are a landlord earning rental income
Receive dividends or investment income
Have foreign income
Earn income from savings, investments, or trusts
Need to claim tax relief or have untaxed income

Key Dates and Deadlines

It’s crucial to keep track of important deadlines to avoid penalties. Here are the key dates you need to remember:

5 October – Deadline to register for Self Assessment Tax Return if you're a first-time filer
31 October – Deadline for submitting paper tax returns
31 January – Deadline for online tax returns and payment of tax owed
31 July – Second payment on account due (if applicable)

Missing these deadlines can result in automatic penalties, starting at £100, so set reminders well in advance.

How to Register for Self Assessment

If this is your first time filing a Tax Return Self Assessment, the first step is to register with HMRC. You can do this online via the HMRC website. After registering, you'll receive your Unique Taxpayer Reference (UTR) number, which you’ll need for all tax-related correspondence.

You’ll also receive an activation code to access your online account. Keep these details safe, as you’ll need them every year.

What Information Do You Need?

To complete your Self Assessment Tax Return, gather the following:

Your UTR number
National Insurance number
Records of self-employment income or other untaxed income
Business expenses and receipts
Bank statements
P60 or P45 forms (if you were employed at any point)
Details of pensions, savings, or investment income
Charity donations or student loan repayments (if applicable)

Having organized records can save you a lot of time and stress. At Stewart Accounting, we recommend maintaining digital records year-round using accounting software or apps that link directly to your bank account.

Step-by-Step Guide to Filing Your Tax Return

Log in to Your Government Gateway Account Use your credentials to access the HMRC portal.
Complete the Relevant Sections Depending on your income sources, you may need to fill in different sections. HMRC's system will guide you based on your situation.
Enter Your Income and Expenses Declare all sources of income and allowable business expenses.
Check for Deductions and Reliefs You might be eligible for tax relief on pension contributions, business expenses, or charitable donations.
Review and Submit Double-check all figures. Once you're satisfied, submit the form electronically.
Make Your Payment Pay any tax owed by the 31 January deadline to avoid interest and penalties.

Common Mistakes to Avoid

First-time filers often make the following errors:

Missing the registration or filing deadline
Forgetting to report all income sources
Misreporting expenses (or claiming disallowed expenses)
Not saving a copy of the completed return
Failing to budget for tax payments in advance

Avoid these mistakes by working with professionals like Stewart Accounting, who can review your return or handle the entire process on your behalf.

How Stewart Accounting Can Help

At Stewart Accounting, we specialise in guiding individuals and small businesses through the Self Assessment Tax Return process. Whether you're self-employed, have complex income streams, or just want peace of mind, our expert team is here to help.

We offer:

Hassle-free registration with HMRC
Accurate record-keeping and digital bookkeeping
Tailored advice on allowable expenses and deductions
Timely reminders and deadline tracking
Full-service filing and tax planning

Don’t let uncertainty hold you back—our goal is to make your Tax Return Self Assessment as smooth and stress-free as possible.

Tips for First-Time Filers

Start early to avoid last-minute pressure
Keep digital records from the start of the tax year
Use HMRC-approved software for easier filing
Seek professional advice if your income sources are complex
Budget for tax payments and set aside funds regularly

Final Thoughts

Filing your Self Assessment Tax Return doesn’t have to be intimidating. With the right preparation and expert guidance, you can stay compliant and even discover opportunities for tax savings. At Stewart Accounting, we’re committed to making the process clear, simple, and efficient—especially for first-time filers.

If you're unsure where to begin or need help completing your Tax Return Self Assessment, contact us today. We’re here to help you file with confidence.

Need Help With Your Self Assessment Tax Return? Get in touch with Stewart Accounting today and take the stress out of tax season.