Associate incorporation decision guide: sole trader vs limited company with the NHS Pension cost (2026/27)

The question generic calculators do not answer

Most incorporation calculators compare income tax plus National Insurance against corporation tax plus dividend tax and declare a winner. For a dental associate working under NHS contracts, that comparison is incomplete. It leaves out the single most valuable benefit of self-employment in NHS dentistry: type-1 practitioner membership of the NHS Pension Scheme.

This guide runs the full comparison at 2026/27 rates and then prices the pension consequence of incorporating, so you can see the real net position.

The 2026/27 rates used in this comparison

All figures below use the following rates, which apply from 6 April 2026 under Finance Act 2026 and earlier legislation.

Income tax: personal allowance £12,570; basic rate 20% to £50,270; higher rate 40% to £125,140; additional rate 45% above. Allowance tapers at £1 for every £2 above £100,000.
Class 4 NIC: 6% on profit between £12,570 and £50,270; 2% above.
Class 2 NIC: £3.45 per week where profit exceeds £6,725 (treated as paid via Self Assessment).
Director salary (Ltd route): £12,570, which sits within the personal allowance and avoids income tax and employee NIC. Employer NIC at 15% applies above the £5,000 secondary threshold, giving £1,135.50 of employer NIC on a £12,570 salary for a single-director company with no Employment Allowance.
Corporation tax: 19% on profits up to £50,000; 25% main rate above £250,000; 26.5% effective marginal rate between £50,000 and £250,000.
Dividend tax: 10.75% (ordinary rate, up to basic-rate band); 35.75% (upper rate, higher-rate band); 39.35% (additional rate). Dividend allowance £500. These rates apply under Finance Act 2026 section 4, rising two points from the 2025/26 rates.
NHS Pension employer-equivalent value: 23.78% of pensionable earnings, being the 23.7% employer contribution rate (in force from 1 April 2024, up from 20.6%) plus the 0.08% administration levy. This is an estimate; the exact employer-side rate is set by the Department of Health and Social Care and can vary between scheme years.

How the sole trader route is taxed

As a self-employed associate, your taxable profit is your associate share of gross fees, less lab costs on your share and other allowable expenses. Income tax applies at the rates above. Class 4 NIC applies on profit between £12,570 and £50,270 at 6% and above £50,270 at 2%. Class 2 NIC of £3.45 per week is treated as paid if profit exceeds £6,725.

Your NHS Pension contributions are deducted at source by the NHS Business Services Authority and are allowable against taxable profit, reducing both income tax and Class 4 NIC. The employer-equivalent value, roughly 23.78% of pensionable earnings, is funded on your behalf by NHS England and the commissioning arrangements. You do not pay it; it accrues as pension benefit on top of your fee income.

How the limited company route is taxed

The company receives the fee income. You draw a £12,570 salary (uses your personal allowance; attracts £1,135.50 of employer NIC at 15% above the £5,000 threshold). The remaining profit, after the salary, employer NIC, your other expenses and an allowance of £1,800 for additional accountancy and admin, is subject to corporation tax. The balance is then distributed as dividends, taxed at the 2026/27 rates above, with a £500 allowance.

No Employment Allowance is available for a single-director company where the director is the sole employee.

The pension layer

This is where the comparison changes for NHS associates.

A self-employed associate performing NHS dental services is normally a type-1 practitioner member of the NHS Pension Scheme. The employer side of the benefit is funded at roughly 23.78% of pensionable earnings. For an associate with £70,000 of pensionable NHS earnings, that is approximately £16,650 a year of employer-funded pension value, on top of fee income.

Bill the same work through a limited company and you generally fall out of the practitioner route. A standard limited company is not an NHS Employing Authority. Income routed through the company does not build NHS Pension benefits in the way it does for a personal performer. The tool prices that forgone employer value as an annual cost of the Ltd route and sets it against the headline tax saving.

Narrow exceptions exist where a company itself holds a GDS or PDS contract and qualifies as an Employing Authority, but these do not apply to a typical associate arrangement.

What the numbers usually show

For a typical NHS-weighted associate, the pension employer value swamps the incorporation tax saving. At £80,000 of net fees with an 80% NHS weighting, the foregone pension value is roughly £15,200 a year, which exceeds the tax saving a limited company generates at those profit levels before the 2026/27 dividend rises are even applied.

The case for a limited company strengthens as the private share of income rises, because private fees are not pensionable in the first place, so there is less pension to forfeit. An associate with a predominantly private book and a high enough profit level can still see a genuine advantage from incorporating.

Other factors that can tilt the decision toward a limited company include: retaining profit in the company rather than extracting everything each year; IR35 not applying to the engagement; employment of a spouse on genuine work at a genuine market salary; a clear exit plan involving Business Asset Disposal Relief on a company share sale. None of these are automatic: each needs to be assessed against your specific situation.

IR35 risk on NHS engagements

IR35 on NHS dental associate agreements is a separate risk on top of the pension cost. If an engagement would look like employment without the company in the way, the off-payroll rules can apply. PAYE becomes due on the fee income and the dividend planning that produces the tax saving disappears, while the pension is still lost. Associate agreements drafted on BDA model terms usually support self-employment, but status depends on working practices, not the contract alone. Take advice if you are in any doubt.

Capital allowances: the same for both routes

Finance Act 2026 extended Full Expensing (100% first-year allowance on qualifying plant and machinery) to all businesses, not just incorporated ones, and introduced a new 40% first-year allowance for assets that do not qualify for Full Expensing. Both routes now have access to the same capital allowance treatment for equipment purchases. This removes one historic advantage of the limited company structure for associates making significant equipment investments.

Business Asset Disposal Relief on exit

From 6 April 2026, Business Asset Disposal Relief applies at 18% on qualifying gains up to a £1 million lifetime limit. A limited company share sale can qualify if the conditions are met (employee or officer for at least two years, 5% shareholding, trading company). A sole-trader cessation does not have the same route to a low CGT rate on goodwill. This is a genuine Ltd advantage for associates planning a sale, but it depends on whether there is meaningful goodwill in the company at exit.

Next steps

Use the calculator on this page to model your own position. Enter your gross fees, fee split, NHS weighting and other figures to see the pension-adjusted verdict for your book of fees. The model is an estimate: take scheme-specific advice from a dental specialist before making any final decision about your trading structure.