The Ultimate Guide to Tax Returns for Self Employed: Everything You Need to Succeed

Jul 18
5 min read

By Sam

Being self-employed is the dream for many. You choose your hours, you pick your clients, and you finally get to call the shots. But as every SME owner knows, that freedom comes with one inevitable houseguest: the tax return.

The phrase "Self Assessment" is enough to make even the most seasoned business owner break out in a cold sweat. It feels complicated, the deadlines are strict, and the jargon: like "payments on account" or "MTD": can feel like a foreign language.

The good news? It doesn’t have to be a nightmare. At Accountant Search, we’ve helped thousands of small business owners navigate the world of tax returns for self employed professionals. This guide is here to break down everything you need to know in plain English, so you can stop worrying about HMRC and get back to growing your business.

What Exactly is a Self Assessment Tax Return?

In a nutshell, a tax return is a form you send to HMRC (His Majesty’s Revenue and Customs) to tell them how much money you earned and what business expenses you had. Since your income isn’t taxed at the source (like it is for employees), HMRC uses this form to calculate exactly how much Income Tax and National Insurance you owe.

You might think you only need to worry about this if you’re a "business," but in the eyes of the taxman, you need to file if:

Your income from self-employment was more than £1,000 (before any tax reliefs) in a tax year.
You’re a partner in a business partnership.
You have other untaxed income, like money from renting out a property or capital gains.

If you’re unsure whether you fit the bill, our tax return accountant services can help clarify your status.

A close-up of a UK tax return form and a magnifying glass, showing a professional and organized approach to finances.

Dates You Cannot Afford to Forget

The UK tax year runs from 6 April to 5 April the following year. Marking your calendar is the first step to success. Here are the "Big Three" dates every self-employed person needs to know:

5 October: This is the deadline to register for Self Assessment if you’re newly self-employed. If you started your business between April 2024 and April 2025, you must register by 5 October 2025.
31 October: This is the deadline for paper tax returns. Most people file online these days, but if you prefer the old-school way, don't miss this one.
31 January: This is the most important date of all. It is the deadline for filing your online tax return and paying the tax you owe. For the 2024/25 tax year, your deadline is 31 January 2026.

Top Tip: Don’t wait until January. HMRC’s phone lines get incredibly busy, and if you hit a technical snag on the 30th, you could face an automatic £100 late penalty: even if you don't owe any tax!

Making Tax Digital (MTD): The Big Change is Coming

If you’ve heard people talking about "MTD," it stands for Making Tax Digital. This is a government initiative to move the whole tax system online.

Currently, most self-employed people file once a year. However, starting from April 2026, if your gross income from self-employment or property is over £50,000, you will be required to:

Keep digital records of all your transactions.
Send quarterly updates to HMRC instead of just one big annual return.
Submit a final declaration at the end of the year.

While this sounds like more work, it’s actually designed to prevent errors and give you a better real-time view of your taxes. Many accounting services for SMEs are already helping clients transition to digital software to stay ahead of the curve.

A tablet showing a modern accounting software dashboard, highlighting the transition to digital record-keeping.

Allowable Expenses: How to Pay Less Tax (Legally)

One of the best parts of being self-employed is that you only pay tax on your profits, not your total turnover. This means you can deduct "allowable expenses" from your income.

Common expenses include:

Office costs: Stationery, phone bills, and broadband.
Travel: Fuel, parking, and train tickets (but not your commute to a regular place of work).
Marketing: Website hosting, business cards, and social media ads.
Working from home: You can claim a proportion of your heating, electricity, and council tax if you work from a home office.
Professional fees: Including the cost of hiring an accountant!

Keeping every single receipt is vital. Whether you use a shoebox or a fancy app, having a record of these expenses is the only way to ensure your tax returns for self employed are accurate and your tax bill is as low as possible.

The "Payment on Account" Surprise

If this is your first year being self-employed, prepare yourself for "Payment on Account." This is often where new business owners get caught out.

If your tax bill is more than £1,000, HMRC assumes you’ll earn a similar amount next year. They ask you to pay half of next year’s estimated tax in January and the other half in July. Essentially, you’re paying your tax in advance. This can mean your first big tax bill is effectively 150% of what you expected. Planning for this cash flow jump is essential for SME growth.

Why You Might Need an Accountant

You can do your tax return yourself. HMRC’s portal is better than it used to be, but it still takes time and precision. Here is why many SMEs choose to work with a professional:

Error Prevention: HMRC can audit you and issue heavy fines for mistakes. An accountant ensures everything is "by the book."
Tax Efficiency: Most business owners miss out on allowable expenses. An accountant often pays for themselves by finding savings you didn't know existed.
Time: How much is an hour of your time worth? If it takes you two days to wrestle with your return, that’s time you aren't spending on your customers. If you're weighing up accountant costs, see How Much Do Accounting Services Cost in the UK? A Complete Pricing Guide for 2026.
Peace of Mind: Knowing a pro has handled it lets you sleep at night.

If you're comparing pricing, our guide to The Ultimate Guide to Accountant Costs in 2026 explains what businesses can expect to pay.

A business owner and an accountant in a collaborative meeting, discussing tax strategy and financial growth.

How to Find Help Near You

Tax laws in the UK are universal, but having someone local can make a huge difference. Whether you need accountants in London, help from accountants in Surrey, or expert accountants in Kent, we make it easy to find a specialist who understands your specific industry.

At Accountant Search, we take the legwork out of finding small business tax services. We match your specific needs: whether it's CIS expertise, VAT advice, or simple Self Assessment: to the right local professional.

Final Thoughts: Don't Let Tax Hold You Back

Tax doesn’t have to be the thing that keeps you from enjoying your business. By staying organized, keeping digital records, and knowing your deadlines, you can take the "assessment" out of Self Assessment.

Ready to take the stress out of your next return? Explore our range of bookkeeping services or use our tool to find local accountants near me today. If you want extra help choosing the right professional, read How to Find an Accountant in the UK: A Step-by-Step Guide for Business Owners. Your future self (especially the one in January) will thank you.