The Limited Company Decision Calculator.

A working Excel Calculator that compares three tax structures — sole-trader, limited-company, and salaried — for UK private medical income, under 2026/27 tax rules. Built for consultants launching private lists, GPs setting up private work alongside the NHS contract, and clinicians weighing the structural decision before incorporating.

What this Calculator is for.

The question "should I run my private practice through a limited company?" is one of the most common in UK medical-tax forums. The answer is not universal — it depends on the absolute level of income, the split between private and NHS earnings, the timing of when income is needed personally, the pension position, and the post-April-2026 dividend rate environment. The right answer for one clinician is wrong for another, and the wrong choice can leave material money on the table either way.

This Calculator does the comparison properly. The user enters their expected private income, NHS income, expense profile, and personal cash needs. The Calculator models the three structural alternatives — sole-trader (Schedule D), limited-company (corporation tax + dividends), salaried-through-existing-employer — and produces a like-for-like comparison of net annual income, multi-year wealth accumulation, and structural flexibility.

What's inside.

Five sheets in a single Excel file, plus an accompanying PDF user guide.

1. Inputs — expected private income, NHS income, expense profile, cash needs
2. Assumptions — UK 2026/27 tax, NI, corporation tax, and dividend parameters, all visible and editable
3. Three-path comparison — sole-trader, limited-company, salaried, modelled side by side
4. Multi-year view — how the comparison evolves over 5 years given retained-earnings strategy
5. Methodology — what the Calculator includes, what it doesn't, and what to discuss with your accountant

What the comparison handles.

UK 2026/27 income tax at 20/40/45% with personal allowance taper above £100,000. Employee NI at 8%/2%. Class 2 and Class 4 NI for sole traders. Corporation tax at small profits, main, and marginal-relief rates. The new dividend tax regime that took effect in April 2026 — 10.75% basic, 35.75% higher, 39.35% additional. Employer NI on salary draw at 15% above the £5,000 secondary threshold. Pension contribution headroom under each structure. Differences in how each structure interacts with the £100,000 personal-allowance taper. Retained-earnings strategy and its multi-year effects.

The full parameter set is visible in the Assumptions sheet and editable for users whose situation requires different defaults.

What you do with the output.

"The case for a limited company is most commonly framed as a tax-saving exercise. Under the post-April-2026 dividend rate regime, the headline tax saving for a high-income clinician is materially smaller than it was three years ago, and it sometimes disappears entirely. The structural case for a limited company — separation of personal and business risk, retained-earnings flexibility, succession planning — often survives the tax-arithmetic shift. The two cases should be analysed separately."

— from the PDF user guide, Reading the comparison

The Calculator's output supports a single decision — which structure to use for private medical income — and three sub-questions: what to draw personally each year, what to retain in the company (if a limited-company route is chosen), and when to review the decision as income levels change.

Who it's for.

• Consultants launching private lists. The structural decision is best made before, not after, the first invoice is issued. The Calculator gives you the substantive analysis your accountant will then refine.
• GPs setting up private work alongside the NHS contract. The interaction with NHS pension and the £100,000 taper is non-trivial. The Calculator models it.
• Clinicians weighing the structural decision before incorporating. The decision is hard to reverse cleanly once made. The Calculator is the framework for making it properly the first time.

What this Calculator is not.

It is a tool, not tax advice. The output is an analytical comparison under stated assumptions, not a recommendation. Tax structure decisions require a qualified accountant who knows your full circumstances — including details the Calculator does not model (carried-forward losses, spouse income, capital allowances, R&D claims where they apply, IHT planning, EIS/SEIS eligibility, and so on). The Calculator's purpose is to make those conversations substantive rather than reactive.

What's related.

• Reading a Private P&L Without Flinching — the Guide that builds the financial literacy for reading your own private practice accounts once it's set up. £39.
• The Locum vs Substantive Calculator — if the question is whether to do private work at all, this Calculator is the analysis that precedes the structural one. £49.