The choice between sole trader and limited company is the first structural decision a UK business makes, and it shapes everything that follows: the tax position, the personal liability exposure, the ability to raise investment, the credibility with enterprise customers, the administrative burden. The decision is reversible (most businesses can switch) but the cost of switching is real, so getting it broadly right at the start saves work later.
This guide covers the comparison end to end. The tax position under each structure. The advantages and trade-offs of incorporating. The Companies House registration process. The duties that come with being a director. The mechanics of transitioning from sole trader to limited company. IR35 and off-payroll working rules. And the closing-down options when the time comes.
Personal liability exposure differs sharply
A sole trader's business and personal assets are legally identical. A limited company is a separate legal entity. For trades involving customer claims, supplier credit, or any service where things can go wrong (and most do), the limited company protection has real economic value.
Tax comparison at typical profit levels
| Profit | Sole trader total tax | Ltd company total tax | Difference |
|---|---|---|---|
| £30,000 | £4,650 | £5,500 | -£850 (sole trader wins) |
| £50,000 | £9,860 | £9,300 | £560 (Ltd wins) |
| £80,000 | £24,000 | £21,600 | £2,400 (Ltd wins) |
| £120,000 | £41,500 | £33,000 | £8,500 (Ltd wins) |
| £200,000 | £79,500 | £58,000 | £21,500 (Ltd wins) |
Illustrative; assumes tax-efficient extraction (small salary plus dividends). Real numbers depend on personal circumstances, pension contributions, dividend allowances, and exact split. The pattern is consistent: at low profits, sole trader is marginally better; at substantive profits, Ltd opens a meaningful gap.
When each structure fits
Sole trader fits when:
- Solo founder with no co-founders.
- Annual profit below £30,000-£40,000.
- No plans to raise external investment.
- Low liability exposure profile.
- Strong preference for administrative simplicity.
Limited company fits when:
- Two or more co-founders.
- Annual profit above £40,000-£50,000.
- Plans for external investment, even speculative.
- B2B customers expecting limited company suppliers.
- Genuine liability exposure (customer claims, supplier credit).
- Tax-efficient extraction strategies (salary + dividends + pension contributions) become valuable.
Incorporation at Companies House
Incorporating costs £50 and takes 24 hours online. The process:
- 1Pick a unique company name (use the Companies House name search).
- 2Choose a registered office address (home, accountant, or registered office service).
- 3Decide directors and shareholders.
- 4Define share capital structure (typically 100 ordinary shares of £0.01 each for a simple company).
- 5Choose articles of association (model articles default; bespoke articles for investment-bound companies).
- 6Submit form IN01 online and pay £50.
- 7Receive certificate of incorporation within 24 hours.
Director duties under the Companies Act 2006
Directors take on legally enforceable duties: act within powers, promote success of the company, exercise independent judgement, exercise reasonable care/skill/diligence, avoid conflicts of interest, not accept benefits from third parties, declare interests in transactions. Most are common-sense for owner-managers but the failure modes (continuing to trade while insolvent, fraudulent preference) trigger personal liability. A director is not a passive role.
IR35 and off-payroll working
For limited company contractors providing services to medium and large businesses, IR35 (the off-payroll working rules) applies. Since April 2021, the engager (not the contractor) is responsible for the status determination. Where the contract is "inside IR35", the contractor is treated as an employee for tax purposes. Where it is "outside", they are treated as a genuine contractor.
The status test considers mutuality of obligation, substitution rights, control, equipment, financial risk, and integration. For long-term assignments at a single client doing similar work to employees, the test typically lands inside IR35.
Transitioning from sole trader to limited company
Many businesses start as sole traders and incorporate later. The mechanics:
- 1Incorporate the new company.
- 2Transfer business assets at market value (capital gains assessed on the sole trader at this point; rollover relief usually available where the trader takes shares in exchange).
- 3Novate contracts from the sole trader to the company (requires customer agreement).
- 4Close the sole trader tax position with HMRC (Self Assessment for the period of trading; cessation entries).
- 5Open new business bank accounts in the company name.
- 6Update VAT registration (transfer or new registration depending on circumstances).
Closing down: MVL vs strike-off
When a limited company is no longer needed:
- Members' Voluntary Liquidation (MVL): formal solvent wind-down. Distributions taxed as capital (CGT/BADR rates). Used for substantial cash distributions where the tax saving versus dividends is material.
- Strike-off (DS01): simpler dissolution where the company has minimal assets and liabilities. Free or low-cost. Distributions during the strike-off process must stay below £25,000 (otherwise they are taxed as income, not capital).
- Liquidation (insolvent): where debts exceed assets; appointing a liquidator becomes a different kind of process.
Structure decision or transition needed?
A Harrow specialist will model the tax position, structure the registration, manage the transition, or close down the company. Free initial assessment.