At some point, almost every self-employed person in the UK ends up searching for a sole trader vs limited company calculator. You plug in your revenue, watch a figure appear, and either feel relieved or quietly alarmed. The number is real — but it’s only part of the picture.

There were 3.0 million sole proprietorships in the UK at the start of 2025, according to GOV.UK business population estimates. A significant proportion of those owners are asking themselves, at various profit levels, whether incorporation would leave more money in their pocket. The calculator gives you a data point. What we’re going to do here is explain what that data point means, what assumptions it’s built on, and what it cannot account for — because those things matter just as much as the headline saving.

The core comparison is straightforward. As a sole trader, you pay income tax on your profits — full stop. As a limited company director, the business pays corporation tax on its profits, and you then extract income through a combination of salary and dividends, each taxed differently.

Most sole trader vs limited company calculator tools for 2026/27 assume a specific extraction strategy for the limited company side: a minimum tax-efficient salary (typically set around the Secondary Threshold for National Insurance) with the remainder drawn as dividends. This is the approach most owner-managed limited companies use in practice, and it genuinely does reduce the overall tax burden compared with paying yourself purely through salary.

Sole traders, by contrast, pay income tax and Class 4 National Insurance on everything above the personal allowance. There’s no dividend option, no splitting the income stream. So as profits rise, the gap between the two structures tends to widen — and that’s what the calculator is measuring.

What it’s not measuring is the cost of getting there, the obligations you take on, or any number of personal and commercial factors that can completely change the calculation in practice.

As a rough guide based on current rates, the tax advantage of a limited company over a sole trader structure becomes meaningful somewhere in the region of £30,000 to £35,000 of annual profit. Below that level, the corporation tax saving is often offset — or more than offset — by higher accounting fees, Companies House obligations, and the administrative burden of running a separate legal entity.

Above £50,000, the difference becomes more significant. Higher-rate income tax bites hard for sole traders, while limited company directors drawing a salary and dividends can often manage their liability more efficiently, particularly if they have a spouse or partner who can also hold shares and benefit from their own dividend allowance and personal allowance.

One calculation that many online tools factor in — and that’s easy to overlook — is the cost of accounting itself. Running a limited company typically costs more to administer than a sole trader setup. One widely cited assumption for 2025/26 tax rates puts annual accounting fees at around £1,300 for a limited company compared to considerably less for a sole trader. That gap is also expected to shift further as Making Tax Digital for Income Tax extends to sole traders from April 2026, increasing their compliance costs. So the net advantage of incorporation isn’t as clean as the headline figure suggests.

It’s worth being clear about what a standard sole trader vs limited company tax calculator assumes, because the output is only as good as the inputs it’s built on.

• One director. Most tools model a single director extracting all the profits. Add a second shareholder and the picture changes — sometimes significantly in your favour.
• Full personal allowance. Calculators assume you’re eligible for the standard personal allowance. If you or your spouse have other income, that assumption may not hold.
• Salary plus dividends. The limited company scenario assumes the optimal extraction mix. In practice, if you’re subject to IR35, you cannot use this strategy — you’d be taxed as an employee on most of your income regardless of structure.
• No pension contributions. Employer pension contributions made through a limited company are a legitimate business expense, which can meaningfully increase the effective take-home figure. Most basic calculators don’t model this.
• A clean profit figure. The calculator needs your profit, not your turnover. If you’re not clear on your allowable expenses, the input — and therefore the output — won’t reflect your real position.

None of this makes the calculator useless. It’s a sensible starting point. But treat the output as a conversation starter rather than a decision-maker.

Tax is important, but it’s rarely the only reason to incorporate — and occasionally not the main one. There are several things a calculator simply cannot weigh up for you.

Limited liability

A limited company is a separate legal entity. Your personal assets are generally protected if the business runs into financial difficulty. For sole traders, there is no such separation — your personal finances are on the line. Depending on your sector and the contracts you take on, this can be a material consideration.

IR35 and your client base

If you’re a contractor working through a limited company, IR35 is a live risk. If HMRC determines your engagements fall inside IR35, the tax advantage of the limited company structure largely disappears — and you could also face a retrospective liability. No calculator models this risk, because it depends entirely on the nature of your work and your contracts.

Perception and credibility

Some clients — particularly larger corporates — prefer to contract with limited companies. Some lenders treat limited company directors differently for mortgage purposes. These factors don’t show up in a tax comparison, but they can influence whether incorporation makes commercial sense.

Admin and ongoing obligations

Running a limited company means annual accounts, a corporation tax return, Companies House filings, confirmation statements, and potentially payroll. The administrative overhead is genuinely higher. For someone who values simplicity above all else, that’s worth factoring in honestly.

Explore the sole trader vs limited company pros and cons in more depth if you want a fuller comparison beyond the tax numbers.