The question of whether you need an accountant for self assessment comes up constantly — in forums, in first-time freelancer groups, and in the first message we get from a lot of new clients. The answer that most accountants give is a predictable one. Ours is a little more nuanced.

The honest truth is that for a small number of people, a straightforward self assessment tax return really is manageable without professional help. But for the majority of self-employed individuals, company directors, landlords, and anyone with more than one income stream, the gap between what HMRC lets you submit and what you should submit — in terms of accuracy, efficiency, and tax saved — is usually wider than people expect.

Here is how we approach this question with our own clients, and what we think is worth knowing before you decide either way.

Let’s be direct about the starting point: there is no legal requirement to use an accountant for self assessment. HMRC’s system is designed so that anyone can register, fill in their SA100, and hit submit. If you have a single employment income and a small amount of untaxed interest, that is genuinely straightforward, and paying an accountant to do it would be hard to justify.

But most people asking this question are not in that situation. They are self-employed, or they have rental income on top of a salary, or they have recently sold an asset, or they have just become a company director and need to declare dividends alongside employment income. None of those are technically complicated in isolation — but add two or three together and the picture changes quickly.

The other thing worth saying is that HMRC’s online system does not tell you what you could have claimed. It only processes what you put in. An accountant’s job is not just to press the button at the end — it is to make sure the numbers going in are right, complete, and optimised. That is a meaningfully different thing.

We would be doing you a disservice if we said everyone needs an accountant. There are situations where handling your own return is entirely reasonable:

• Single employment income only. If your only income is from a PAYE job and you are filing simply to report a small savings interest or a one-off gift above the threshold, the return is brief and the scope for error is limited.
• Very simple self-employment with clean records. If you are a sole trader with a handful of invoices, minimal expenses, and you have kept tidy records throughout the year, a basic return is manageable.
• You have done it successfully before. If your circumstances have not changed year on year and your previous returns were accurate, there is less risk in continuing to handle it yourself.

The key word throughout is simple. As soon as your income picture becomes layered — different sources, different tax treatments, reliefs to claim, payments on account to manage — the case for DIY starts to erode. Not because the system is impossible to navigate, but because the cost of getting it wrong, or of missing something you were entitled to claim, tends to outweigh the cost of getting help.

In our experience, the situations where professional support makes a measurable difference include the following:

Self-employed or freelance income

Knowing which expenses are allowable, how to handle capital allowances, and whether your accounting method is working in your favour are all things that are easy to get slightly wrong — and slightly wrong tends to mean paying more tax than you owe.

Multiple income sources

A salary plus freelance work plus rental income is a common combination for a lot of people in their thirties and forties. Getting the interaction between those income streams right, and understanding how they affect your tax bands and personal allowance, is where it becomes genuinely worth having someone who has seen it before.

Income above £100,000

Once your income crosses £100,000, your personal allowance starts to taper away at a rate of £1 for every £2 earned above that threshold. There are legitimate planning steps — such as pension contributions — that can change the position significantly. Without advice, many people in this bracket overpay.

Company directors

If you are a director drawing a salary and dividends, your self assessment interacts with your company’s corporation tax position. These are not independent filings and should not be treated as such.

Capital gains, rental income, or previous errors

All three introduce complexity that the basic HMRC guidance does not handle particularly well. If you have sold a property, a business, or shares, or if a previous return contained mistakes you want to correct, an accountant is the right call.

There is a broader shift underway that is worth factoring into your thinking. Making Tax Digital for Income Tax (MTD for IT) is being rolled out in stages over the next few years. From April 2026, it becomes mandatory for individuals with qualifying income over £50,000. The threshold drops to £30,000 from April 2027, and to £20,000 from April 2028.

What this means in practice is that the days of filing a single annual return for a lot of self-employed people and landlords are numbered. MTD requires quarterly digital submissions of income and expenses using compatible software, followed by a year-end declaration. That is a more involved process than the current system, and it raises the bar on record-keeping, software familiarity, and compliance management.

HMRC has said it will write to taxpayers when their obligation to move to MTD is approaching — but it is also clear that the responsibility to comply sits with the taxpayer. Missing the transition, or submitting quarterly updates incorrectly, carries penalties.

For anyone who is already borderline on whether professional support makes sense, MTD tilts the calculation noticeably. Managing the quarterly rhythm of submissions alongside running a business is something most people find easier — and less error-prone — with a bit of support behind them.

One reason people hesitate to bring in an accountant is the assumption that it will be expensive. That is sometimes a fair concern — but it is worth knowing what the market actually looks like.

At Wings Online Filings, our self assessment tax return service is a fixed fee of £150, which covers preparation of your SA100 and SA302, income from multiple sources, claiming applicable allowances and reliefs, payments on account advice, and timely submission to HMRC. There are no hidden extras.

The more useful question is not what it costs, but what the alternative costs. If you spend three or four hours working through a return yourself, make a claim you were not entitled to, miss one you were, or submit late because life got in the way, the arithmetic tends to move in the accountant’s favour fairly quickly. A penalty for a late return starts at £100 on the day it is overdue, and that is before HMRC starts calculating interest on unpaid tax.

We are not suggesting everyone needs to outsource everything. But on a straightforward self assessment, the numbers rarely make the DIY case as clearly as people expect when they sit down and run them honestly.