The question comes up constantly: “should I incorporate?” And increasingly, the first thing people do is run a sole trader vs limited company calculator to see how much tax they might save. That is a reasonable instinct. Knowing the numbers before you make a structural decision is sensible, not premature.

But calculators have limits. They show you a headline tax saving — and sometimes a meaningful one. What they cannot show you is whether the admin overhead, the accountancy cost, the loss of simplicity, and the public filing obligations are worth it at your particular stage of growth. We have seen clients incorporate too early and regret it. We have also seen clients stay as sole traders far longer than made sense. The calculator is not wrong; it is just incomplete.

So in this post we want to walk through what a comparison of the two structures actually involves in 2026/27 — the real rates, the real trade-offs, and the point at which the maths tends to tip decisively in one direction.

When you plug a profit figure into a sole trader vs limited company calculator, it is running two parallel tax computations and showing you the difference. On the sole trader side, it applies Income Tax and Class 4 National Insurance to your taxable profit. On the limited company side, it applies Corporation Tax to the company’s profit, then models a salary and dividend combination to extract that profit to you personally.

For 2026/27, the key rates look like this:

• Income Tax: 20% basic rate, 40% higher rate, 45% additional rate (applied to your sole trader profit above the £12,570 personal allowance)
• Class 4 National Insurance: 6% on profits between £12,570 and £50,270, 2% above that
• Corporation Tax: 19% on profits up to £50,000 (small profits rate), rising to 25% for profits above £250,000
• Dividend tax: 10.75% basic rate, 35.75% higher rate, 39.35% additional rate — with a £500 dividend allowance before tax applies

The saving, where it exists, comes primarily from the gap between the combined Corporation Tax and dividend tax rate versus the Income Tax and NI rate you would pay as a sole trader. At higher profit levels — typically above £30,000 to £35,000 net profit — that gap can be meaningful.

There is no universally correct profit threshold, but in our experience the numbers start to favour a limited company somewhere around £30,000 to £40,000 of annual profit — and the case strengthens considerably above £50,000. Below that level, the difference is often smaller than people expect, particularly once you account for the extra accountancy cost of running a company.

Here is a simplified illustration. A sole trader earning £50,000 profit in 2026/27 would broadly pay Income Tax and Class 4 NI on the amount above their personal allowance. A director-shareholder extracting the same economic value through a limited company — taking a salary up to the National Insurance threshold and drawing the remainder as dividends — will typically pay Corporation Tax on the company profit and dividend tax on distributions, but at combined rates that are lower than the equivalent Income Tax and NI.

The dividend allowance for 2026/27 is £500, which means only the first £500 of dividends each year is free of dividend tax. That is considerably lower than it was a few years ago, so the saving is not as dramatic as older calculators might suggest. Anyone using a tool that has not been updated to reflect current rates should treat the output with caution.

One thing the calculator does not model well: if you are planning to leave profit in the company rather than drawing it all out, the tax deferral benefit can be significant — but that only matters if you genuinely have the discipline and business reason to leave cash in the company.

This is where the conversation usually gets more useful. The tax saving — real as it may be — sits alongside a set of costs and obligations that the calculator ignores entirely.

Accountancy costs

A sole trader needs a Self Assessment tax return. At Wings, that is £150. A limited company needs year-end accounts, a Corporation Tax return (CT600), a Confirmation Statement, and usually a director’s Self Assessment as well. That is a meaningfully higher compliance burden. If the additional accountancy cost eats a significant portion of your projected tax saving, incorporation is harder to justify on financial grounds alone.

Administration and filing obligations

Limited companies file accounts at Companies House — those accounts are public. Your turnover, profit, and balance sheet are visible to anyone who searches for your company. For some business owners that is fine; for others it matters. Directors also carry legal responsibilities that sole traders do not.

Flexibility and access to money

As a sole trader, profit is yours. As a director-shareholder, money belongs to the company first. Drawing a salary or dividend requires proper process and record-keeping. If your cash flow is unpredictable or you need flexibility in how you access funds, the structure of a limited company adds friction.

None of these are reasons to avoid incorporating — they are just things the number on a calculator does not show you.

ONS data from March 2025 shows that the number of UK businesses structured as companies grew by 1.8% year-on-year, while the number of sole proprietors fell by 4.1% over the same period. Companies now represent more than three-quarters of all registered VAT and PAYE businesses in the UK.

That shift is partly tax-driven and partly a reflection of how businesses want to present themselves — limited companies can feel more credible to certain clients, particularly in professional services and contracting. The largest single industry group for registered businesses is professional, scientific, and technical services, which also happens to be the sector where incorporation often makes the most financial sense.

We are not suggesting you incorporate because everyone else is. But the trend does reflect the fact that for a growing number of UK business owners, the maths and the optics point in the same direction. If you are a freelancer or contractor working with larger organisations, some clients and agencies will only engage limited companies — which can make the decision for you regardless of the tax calculation.

If IR35 applies to your work, the picture becomes considerably more complex. In that case, a proper understanding of IR35 needs to come before any structural decision, because incorporating while caught by IR35 does not deliver the tax benefits the calculator predicts.

Our recommendation is to treat any sole trader vs limited company tax calculator as a first filter, not a final answer. Here is how to get the most from it:

• Use your net profit, not turnover. The comparison is about taxable profit after expenses, not your top-line revenue.
• Check the rates are current. Dividend tax rates changed in April 2026. The dividend allowance has been cut substantially from its historical levels. If the tool does not reference 2026/27 specifically, its output may be materially wrong.
• Factor in the additional compliance cost. If you are currently doing your own Self Assessment, ask yourself what it will cost to have a company’s accounts, CT600, and Confirmation Statement prepared properly. That cost belongs in your comparison.
• Think about what you will actually draw. The tax saving is most powerful when you can leave money in the company and draw it strategically. If you need every pound you earn to cover living costs, the saving shrinks considerably.
• Consider the full picture. Liability protection, business credibility, funding options, and long-term exit planning all sit outside the calculator’s scope — but they may be the most important factors for your situation.

For a deeper look at how the two structures compare across all the key dimensions, our guide on sole trader vs limited company covers the ground in more detail.