If you are a freelancer working through recruitment agencies in the UK, the choice between operating as a limited company vs sole trader is not just a tax calculation. It is a decision shaped by how agencies engage you, whether your contracts fall inside or outside IR35, and what your medium-term earnings trajectory looks like.

Most online comparisons focus on headline tax rates. They show you the 19% corporation tax versus 20% income tax, or the dividend tax rates versus self-employed National Insurance. That is useful, but it misses the real constraint: many agencies will only work with limited company contractors, or they will default to umbrella company arrangements unless you push back. Your structure choice starts with what the agency contract allows.

As ICAEW qualified accountants working with freelancers across every sector from tech contractors in Shoreditch to creative freelancers in the Northern Quarter, we see the same pattern. The structure that works best depends on three things: your IR35 status, your agency's preferred engagement model, and your earnings level. Here is how to work through each one.

How Agencies Engage Freelancers: The Three Routes

When you work through a recruitment agency, there are typically three engagement models the agency will offer you. Understanding these is the foundation of the limited company vs sole trader decision.

Route one: Limited company (PSC). The agency contracts with your personal service company. You invoice the agency through your limited company. You are responsible for your own tax, NI, and dividend planning. This is the traditional contractor model.

Route two: Umbrella company. The agency places you on an umbrella company's payroll. The umbrella handles PAYE, NI, and pension deductions. You receive a net salary. This is the default option for many agencies when IR35 applies or when the contractor does not have a limited company.

Route three: Sole trader / self-employed. The agency contracts with you as an individual. You invoice them as a sole trader. You file self assessment returns and pay Class 2 and Class 4 National Insurance. This is less common for agency work, but it exists, particularly in creative industries and shorter-term engagements.

Your first question to any agency should be: "What engagement models do you support for contractors?" If they say limited company only, the decision is made. If they offer both limited company and sole trader, you then work through the tax and IR35 implications.

IR35: The Single Most Important Factor

IR35 determines whether your contract is treated as employment for tax purposes, even though you are working through your own company. If you are inside IR35, the limited company tax advantages largely disappear. You pay tax and NI on almost everything you earn, similar to being an employee.

For agency freelancers, IR35 status is typically determined by the end client, not the agency. Since April 2021, medium and large clients are responsible for issuing a Status Determination Statement (SDS). If the SDS says "inside IR35", the agency must deduct PAYE and NI from your payments before they reach your company.

Here is the practical impact on the limited company vs sole trader decision:

  • If your contract is outside IR35: A limited company is almost always the better option. You retain the profits in the company, pay corporation tax at 19% or 25% instead of income tax at 20% or 40%, and extract profits as dividends taxed at 8.75% or 33.75%. The overall effective tax rate on profits extracted is typically 20-30% lower than equivalent self-employed income.
  • If your contract is inside IR35: The limited company advantage is minimal. You pay PAYE and NI on your deemed employment income, plus employer NI at 13.8%. You may keep a small margin of retained profit, but the tax saving is often not worth the additional compliance cost. Many contractors in this position switch to an umbrella or operate as a sole trader if the agency allows it.
  • If your contract status is uncertain: This is the trickiest scenario. If you have a mix of inside and outside IR35 contracts, a limited company can still work. You draw a salary from the inside-IR35 income and take dividends from the outside-IR35 income. But the compliance burden is higher, and you need an accountant who understands the interaction.

Tax Comparison: Limited Company vs Sole Trader for 2025/26

Let us run the numbers on a typical scenario. You are a freelance consultant in Bristol earning £80,000 per year through agency contracts. You have no significant business expenses beyond your home office, software subscriptions, and professional insurance.

Sole Trader on £80,000

  • Turnover: £80,000
  • Expenses: £3,000 (home office, software, insurance, accountancy)
  • Net profit: £77,000
  • Personal allowance: £12,570
  • Basic rate tax (20% on £37,700): £7,540
  • Higher rate tax (40% on £26,730): £10,692
  • Class 4 NI (9% on £37,700, then 2% on £39,300): £3,393 + £786 = £4,179
  • Class 2 NI: £179.40
  • Total tax and NI: £22,590
  • Net income: £54,410

Limited Company on £80,000 (outside IR35)

  • Company turnover: £80,000
  • Company expenses: £3,000 (including director salary)
  • Director salary: £12,570 (no tax or NI due as it is within personal allowance and primary threshold)
  • Company profit before tax: £64,430
  • Corporation tax (19% on first £50k, 25% on £14,430): £9,500 + £3,607.50 = £13,107.50
  • Profit after tax: £51,322.50
  • Dividend taken: £51,322.50
  • Dividend allowance: £500
  • Dividend taxed at basic rate (8.75% on £37,700): £3,298.75
  • Dividend taxed at higher rate (33.75% on £13,122.50): £4,428.84
  • Total tax and NI: £13,107.50 + £3,298.75 + £4,428.84 = £20,835.09
  • Net income: £59,164.91

In this example, the limited company saves you approximately £4,750 per year in tax. That is before accounting for the additional compliance costs of running a limited company (annual accounts, confirmation statement, corporation tax return, payroll RTI filing). Those costs typically run £800 to £1,500 per year with a good accountant. The net saving is still meaningful, around £3,250 to £3,950.

But here is the catch. That saving only exists if your contract is outside IR35. If it is inside IR35, the limited company calculation changes dramatically. You would pay PAYE and NI on the deemed employment income, and the net saving shrinks to a few hundred pounds or disappears entirely.

When a Sole Trader Makes More Sense

There are specific scenarios where staying as a sole trader is the better move, even if the tax calculation favours a limited company on paper.

Scenario one: Low earnings. If your annual turnover is below £30,000, the compliance cost of a limited company eats into any tax saving. The flat rate of corporation tax at 19% on small profits is not that different from basic rate income tax plus NI. And you avoid the hassle of Companies House filings, payroll RTI submissions, and dividend paperwork.

Scenario two: Inside IR35 contracts only. If every agency contract you take is inside IR35, there is little point incorporating. You end up paying broadly the same tax as a sole trader or umbrella employee, but with more paperwork. Some contractors in this position still incorporate for limited liability protection, but the tax case is weak.

Scenario three: Short-term or intermittent work. If you take contracts for three months then have two months off, the fixed costs of a limited company (accountancy fees, software subscriptions, Companies House filing) are harder to justify. A sole trader can simply file a self assessment return and pay tax on the profit.

Scenario four: You want simplicity. Sole trader accounting is straightforward. One self assessment return per year. No separate company bank account. No payroll. No dividend paperwork. For freelancers who hate admin, that simplicity has real value.

When a Limited Company Is the Right Move

The limited company structure shines in these situations:

  • Outside IR35 contracts above £50,000. The tax saving becomes material. At £80,000, you save around £4,000 per year. At £120,000, the saving grows to £8,000 or more.
  • Multiple contracts simultaneously. A limited company can hold multiple contracts, retain profits, and time dividend extraction to minimise higher rate tax. A sole trader pays tax on all profit in the year it is earned.
  • You want to build retained profits. A limited company can retain profits for future investment, equipment purchases, or pension contributions. A sole trader cannot defer tax in the same way.
  • You want limited liability. If your work carries professional risk (consultancy, IT infrastructure, financial advice), the limited company structure protects your personal assets. A sole trader is personally liable for any claims.
  • You plan to take on employees. A limited company can employ staff, including your spouse, and claim the Employment Allowance against employer NI. A sole trader can employ staff too, but the structure is less tax-efficient for family tax planning.

The Agency Contract: What to Check Before You Decide

Before you incorporate or register as a sole trader, check your agency contract for these clauses:

Preferred engagement model. Some agencies specify that they only engage limited company contractors. Others prefer umbrella companies. A few accept sole traders. If the agency insists on a limited company, your decision is made. If they accept both, you have flexibility.

IR35 status clause. The contract should reference whether the end client has issued an SDS and what the determination says. If the contract says "inside IR35" but you believe the role is outside, you can challenge the determination through the client's status disagreement process. Do not just accept it without checking.

Payment terms. Limited companies typically invoice monthly and get paid within 30 days. Sole traders often invoice on completion of work. Check whether the payment cycle works for your cash flow. A limited company that needs to pay corporation tax 9 months after year-end needs consistent cash flow.

Insurance requirements. Many agency contracts require professional indemnity insurance and public liability insurance. A limited company can take out these policies in the company name. A sole trader needs personal policies. The cost is similar either way.

What About the Umbrella Company Option?

If you decide against a limited company and the agency does not accept sole traders, the umbrella company route is the default. Umbrella companies handle all your tax and NI deductions. You receive a net salary with PAYE already applied. There is no self assessment filing (in most cases) and no company compliance.

The downside is cost. Umbrella companies charge a margin, typically £20 to £30 per week, and you pay full employee and employer NI on your earnings. The effective tax rate is higher than both a limited company (outside IR35) and a sole trader. Umbrella companies are best suited to inside-IR35 contracts where the tax difference is minimal.

If you are considering an umbrella, check whether the agency has a preferred supplier list. Some agencies only work with specific umbrella companies. Others let you choose your own. And be wary of umbrella companies offering "tax efficient" schemes that involve loan arrangements or other structures. HMRC is actively challenging these, and the risk of a tax bill plus penalties is real.

Practical Steps to Decide

Here is a straightforward process to choose between limited company and sole trader status as an agency freelancer:

  1. Ask the agency what engagement models they support. This is your first filter. If they only accept limited companies, incorporate. If they accept both, move to step two.
  2. Get the IR35 status determination from the end client. If the role is inside IR35, a limited company offers little tax advantage. If it is outside IR35, the limited company structure is worth considering.
  3. Estimate your annual turnover. If it is below £30,000, the compliance cost of a limited company often outweighs the tax saving. Above £50,000, the tax saving becomes meaningful.
  4. Consider your medium-term plans. If you plan to grow your business, take on employees, or retain profits for investment, a limited company gives you more flexibility. If you plan to stay as a solo freelancer with no growth ambitions, a sole trader is simpler.
  5. Run the numbers with an accountant. A proper comparison needs your specific expenses, pension contributions, and dividend strategy. Our ICAEW qualified team can run that comparison for you. Contact us to book a consultation.

Can You Switch Later?

Yes. Many freelancers start as sole traders and incorporate once their earnings cross the £50,000 threshold or when they secure an outside-IR35 contract. The process is straightforward. You register a new limited company with Companies House, notify HMRC, and transfer your contracts to the company.

There are two things to watch. First, if you have built up goodwill or a client list as a sole trader, transferring those to your limited company can trigger a capital gain. Second, you cannot simply stop being a sole trader. You must notify HMRC and file a final self assessment return showing the date you ceased self-employment.

The reverse switch, from limited company back to sole trader, is more complicated. You need to close the company, distribute the retained profits (which triggers dividend tax), and settle any outstanding corporation tax. It is doable, but the exit costs mean you should be confident in your decision before incorporating.

Final Verdict

For most agency freelancers earning between £50,000 and £150,000 on outside-IR35 contracts, a limited company is the better option. The tax saving is material, the limited liability protection is valuable, and the flexibility to retain profits and plan dividends is worth the extra compliance.

For freelancers on inside-IR35 contracts, or those earning below £30,000, a sole trader structure is usually simpler and cheaper. The tax difference is small, and the admin burden is lower.

The key is to make the decision based on your specific contract terms and earnings, not on generic tax comparisons. Start with your agency contract. Check the IR35 status. Then run the numbers. And if you need help working through it, our services page explains how we support freelancers with both structures.

If you are ready to incorporate, our incorporation guide walks you through the process step by step. And if you want to understand the tax implications in more detail, our limited company tax blog covers dividend planning, salary extraction, and corporation tax planning for freelancers.