Everything You Need to Know About Filing UK Self-Assessment Tax Returns

Filing a Self-Assessment Tax Return can feel daunting, but it doesn’t have to be! Whether you’re a sole trader, landlord, freelancer, or company director, ensuring your tax return is filed correctly and on time is crucial to avoiding penalties and maximising tax savings.

At Black & White Accounting, we help you navigate the process smoothly, ensuring you don’t pay a penny more than necessary while staying fully compliant with HMRC. Here’s everything you need to know about Self-Assessment Tax Returns in the UK and why working with an accountant can save you time, money, and stress.

What is a Self-Assessment Tax Return?

The Self-Assessment Tax Return (SA100) is how individuals report their income, expenses, and tax liabilities to HMRC. Unlike employees who have tax deducted through PAYE, self-employed individuals and others with untaxed income must calculate and pay their own tax.

Who Needs to File a Self-Assessment Tax Return?

You must file a Self-Assessment tax return if you: ✅ Are self-employed and earned over £1,000 in a tax year. ✅ Are a landlord earning rental income over £2,500 after expenses. ✅ Are a company director and receive untaxed income. ✅ Earn over £100,000 from any source (employment, self-employment, rental income, etc.). ✅ Earn over £50,000 and claim Child Benefit (due to the High Income Child Benefit Charge). ✅ Receive foreign income or have complex tax affairs. ✅ Have significant investment income beyond tax-free allowances.

Even if you’re not sure whether you need to file, it’s always best to double-check with an expert—missing a required return can result in hefty fines!

Key Deadlines for Self-Assessment

Missing a deadline can lead to fines, so mark these dates in your calendar! 📌 5 October – Register for Self-Assessment (if it’s your first time filing). 📌 31 October – Paper tax return deadline. 📌 31 January – Online tax return deadline & payment deadline for any tax owed. 📌 31 July – Payment deadline for second payment on account (if applicable).

Penalties for Late Filing: ❌ £100 fine for filing 1 day late. ❌ Additional fines if over 3 months late. ❌ Interest on unpaid tax—HMRC doesn’t forget!

How to File a Self-Assessment Tax Return

1️⃣ Register with HMRC – If this is your first time, register for Self-Assessment and get your Unique Taxpayer Reference (UTR). 2️⃣ Gather Your Financial Records – This includes income, expenses, invoices, bank statements, and P60s/P45s if employed. 3️⃣ Claim Allowable Expenses – Business owners can deduct costs like travel, home office expenses, equipment, and more. 4️⃣ Calculate Your Tax Liability – HMRC will determine what you owe based on your reported income and expenses. 5️⃣ Submit Your Return – File online through HMRC’s portal or let an accountant do it for you. 6️⃣ Pay Your Tax Bill – Ensure payments are made on time to avoid penalties.

Why You Need an Accountant Like Black & White Accounting

Filing a tax return might seem simple, but one mistake can cost you hundreds or even thousands of pounds. That’s where we come in!

✅ Save Time & Avoid Stress – No need to wrestle with tax jargon or complex forms. ✅ Maximise Tax Reliefs & Allowances – We ensure you claim every possible deduction to reduce your tax bill. ✅ Avoid Costly Mistakes & Penalties – We double-check everything, so you don’t overpay or get fined. ✅ Plan for Future Tax Bills – We provide tax-planning advice so you’re never caught off guard. ✅ Expert Help with Complex Cases – From landlords and business owners to investors and high earners, we tailor our service to your needs.

Common Self-Assessment Mistakes to Avoid

🚨 Missing the Deadline – Even one day late means a fine! 🚨 Forgetting to Declare All Income – HMRC cross-checks data, so undeclared income can lead to investigations. 🚨 Not Claiming Allowable Expenses – Many business owners overpay tax because they don’t claim all deductions. 🚨 Entering Incorrect Figures – Small mistakes lead to incorrect tax bills and potential penalties. 🚨 Failing to Budget for Tax – Self-employed individuals must plan for January and July tax payments.

Let’s Make Self-Assessment Simple!

At Black & White Accounting, we make tax season stress-free, efficient, and cost-effective. Whether you need help filing your return or just want to reduce your tax bill legally, we’re here for you.

📞 Get in touch today and let us handle your tax return—so you can focus on growing your business instead of crunching numbers!