For a straightforward return, no: you do not need an accountant for Self Assessment. HMRC’s online service was built for individuals, current GOV.UK guidance explains each section, and someone with one source of income and tidy records can usually complete their return in an evening. The calculation is done for you. Where the honest answer shifts is when the return stops being a form-filling exercise and becomes a series of judgement calls: what counts as allowable, which reliefs apply, how different income types interact. That line is crossed more easily than most people think.

The single-source return: genuinely DIY territory

If your Self Assessment exists for one clean reason (self-employment with simple expenses, or a modest rental, or untaxed income alongside a salaried job), self-filing is realistic. What makes it go smoothly is preparation rather than expertise: records kept during the year as GOV.UK guidance describes, paperwork gathered before you sit down, and honest attention to the questions rather than racing to the end. People who file this way year after year mostly do fine.

When the return becomes judgement calls

The character of Self Assessment changes when several of these stack up:

  • Self-employment income with expenses that need categorising and defending
  • Property income, especially more than one property or partial-year lets
  • Dividends and salary from your own company, where the mix was a choice
  • Capital gains from selling assets, shares or property
  • Foreign income or non-UK residence questions
  • Pension contributions and reliefs worth claiming properly
  • Income crossing thresholds where charges and tapers apply

Each item alone is learnable. In combination they interact, and the cost of a wrong interaction (relief unclaimed, income misreported, a charge missed) is usually a multiple of an accountant’s fee. This is the point where paying for preparation stops being a luxury.

What you are actually buying from an accountant

A professionally prepared return is not just data entry. The fee typically covers: a review of what you can claim that you did not know to claim; correct treatment of anything unusual this year; the payments-on-account position explained before it surprises you; filing as your authorised agent; and someone to answer HMRC if a letter arrives. Many clients find the first year pays for itself in found reliefs, and later years buy time and certainty rather than discoveries. Sole traders weighing this alongside bookkeeping should read does a sole trader need an accountant?; the DIY question in full lives in can I do my small-business accounts myself?

Signals it is time to stop self-filing

Experience suggests these are the reliable ones:

  • You finished last year’s return unsure whether it was right
  • Your refund or bill differed sharply from expectations and you cannot say why
  • This year contains a first: first property sale, first dividends, first foreign income
  • You filed late, or nearly late, because you dreaded starting
  • The time you spend on the return now exceeds what a preparer would charge for it

One signal is worth noting; two or more is your answer. The main guide to whether your small business needs an accountant places Self Assessment within the bigger decision.

Frequently asked questions

Is Self Assessment hard to do yourself?

For a single income source with good records, no. The online service guides you through and calculates the tax. Difficulty scales with the number and type of income sources, not with the form itself.

Will an accountant get me a bigger refund?

No honest accountant promises that. What they do is claim everything you are entitled to and nothing you are not, which often improves on DIY in both directions.

Can an accountant file if I have already registered myself?

Yes. Your accountant is added as your authorised agent, and your existing registration carries on unchanged.

What records should I keep for my return?

Records supporting every figure you enter (income evidence, expense receipts, statements), kept for the periods set out in current GOV.UK guidance. Good records are what make either DIY or professional preparation cheap.

Do I need an accountant every year, or just complicated years?

One-off engagements are normal. Some clients use us only for years with a sale, a windfall or a change, and self-file the quiet years. Any decent firm will support that pattern.

When you are ready to hand it over

Our Self Assessment service covers preparation, review, filing and HMRC correspondence, priced by the complexity of your actual return. Request a quote and list your income sources. That is all we need to price it accurately.