If you’re running a small business as a sole trader, you’ve probably asked yourself at some point whether you actually need an accountant — or whether you could just file your own Self Assessment and save the fee. It’s a reasonable thing to question, especially when you’re watching every pound of expenditure.

The honest answer is that plenty of sole traders do manage their own tax affairs perfectly well. And some of them overpay, miss deductions, or spend far more time on admin than they realise. The question “do I need an accountant as a sole trader” is really two questions at once: can you do it yourself, and should you? Those aren’t always the same thing.

We’ve worked with sole traders across Hampshire and the wider UK for over 20 years, and we see a consistent pattern. The ones who benefit most from professional support aren’t necessarily the ones with the most complex businesses — they’re the ones who’ve recognised what their own time is worth, and what a tax mistake actually costs.

Before deciding whether to hire an accountant, it helps to be clear on what the compliance picture actually looks like. As a sole trader, you’re required to register for Self Assessment, keep records of all business income and expenses, and file an SA100 tax return each year by 31 January for the prior tax year. You must also keep records of any personal income that might affect your tax position.

From the 2024 to 2025 tax year, cash basis became the default accounting method for sole traders — meaning you record income when you receive it and expenses when you pay them, rather than when invoices are raised. That simplifies things for most people, but it isn’t always the right approach for every business, and switching methods later can create complications.

On top of that, if your taxable turnover exceeds £90,000, VAT registration becomes compulsory. And from April 2026, Making Tax Digital for Income Tax applies to sole traders with qualifying income above £50,000, dropping to £30,000 from April 2027. Under MTD, you’ll need to submit quarterly digital updates to HMRC alongside your end-of-year return, using HMRC-recognised software. That’s a meaningful change in the administrative burden for many sole traders who’ve managed fine with a spreadsheet until now.

None of this is insurmountable without an accountant, but the question is whether handling it all yourself is the best use of your time — and whether you’re confident you’re doing it correctly.

Self-filing is entirely legal and, for a straightforward sole trader with simple income and no employees, often works fine. Where it tends to go wrong is at the edges — the claims people aren’t sure about, the income they don’t realise they need to declare, and the deadlines that sneak up.

The most common areas we see mistakes in practice:

• Allowable expenses — home office costs, vehicle use, professional subscriptions, and equipment all have specific rules about what you can claim and how. Over-claiming is a compliance risk; under-claiming means paying more tax than you need to.
• Payments on account — HMRC collects tax through two payments on account each year (in January and July), based on the prior year’s liability. Many first-time filers don’t anticipate the size of these and face a cash flow shock.
• Sole trader to limited company transitions — if you’ve moved between trading structures, or have income from multiple sources, the return becomes considerably more involved.
• Record-keeping gaps — HMRC can request business records going back several years. Incomplete or inconsistent records make an enquiry much harder to defend.

These aren’t rare edge cases. They come up regularly, and the cost of getting them wrong — whether in additional tax, penalties, or HMRC interest — tends to exceed what an accountant would have charged.

It’s worth being specific here, because “accountant” covers a lot of ground. For a sole trader, a good accountant should be doing more than keying figures into a tax return once a year.

At the core, they’ll review your records, ensure your accounts are prepared accurately, identify all allowable deductions, and file your Self Assessment return on your behalf. They’ll deal with HMRC correspondence, manage your payments on account, and flag anything unusual before it becomes a problem.

Beyond compliance, a decent accountant will help you understand what your tax bill is likely to be before January — so you can plan for it. They’ll advise on whether you should register for VAT voluntarily, whether the flat rate scheme might benefit you, and whether your current trading structure still makes sense as your income grows.

With Making Tax Digital coming into effect for higher-earning sole traders from April 2026, accountants are also helping clients set up the right software, understand what the quarterly updates require, and make sure the digital link between their records and HMRC submissions is compliant. MTD’s quarterly updates are summaries of income and expenses — they’re not quarterly tax payments — but getting them wrong or missing them still carries a penalty risk.

In our experience, the value of a good accountant compounds over time. The longer someone has a clear picture of their finances, the better the decisions they make around pricing, investment, and growth.

We’d be doing you a disservice if we said everyone needs an accountant. Some sole traders genuinely don’t, at least not at the start.

If your income is from a single source, your expenses are simple and well-documented, your turnover is well below the VAT threshold, and you’re comfortable with the Self Assessment process, then a capable person with an organised spreadsheet and a bit of time can handle their own return. HMRC’s online system is reasonably straightforward for basic cases, and some cloud accounting tools — including options like QuickBooks Sole Trader and FreeAgent — do a reasonable job of guiding you through the process.

That said, even in simple cases, a one-off review with an accountant when you first start trading can pay for itself. Getting your records set up correctly from day one, understanding what you can and can’t claim, and knowing your obligations on things like National Insurance is worth more than most people realise before they’ve been through a tax enquiry.

The calculus tends to change as income grows, the business becomes more complex, or MTD obligations kick in. Once you’re dealing with quarterly digital submissions, employees, or multiple income streams, the administrative load alone shifts the cost-benefit calculation — and that’s before considering the tax planning opportunities that become available at higher income levels.