IR35 Calculator: Inside vs Outside
2026/27Enter your day rate to see exactly how much you take home working inside IR35 via an umbrella company versus outside IR35 through your own limited company. Includes employer NI, corporation tax, and the optimal salary-dividend split.
What is IR35?
IR35 — formally known as the off-payroll working rules — is UK tax legislation designed to combat disguised employment. It was first introduced in 2000 (as Inland Revenue press release 35, hence the name) and significantly reformed in April 2017 for the public sector and April 2021 for medium and large private sector clients.
IR35 targets contractors who provide services through an intermediary (typically a personal service company, or PSC) but work in a way that is functionally indistinguishable from an employee. If HMRC considers your engagement to fall inside IR35, your income is treated as employment income — subject to PAYE income tax and National Insurance — rather than as company profits that can be extracted as tax-efficient dividends.
The rules hinge on three key tests: substitution (can you send someone else to do the work?), control (does the client control how you work?), and mutuality of obligation (is there an ongoing expectation of work?). A genuine contractor typically passes all three, placing them outside IR35.
Inside IR35 vs Outside IR35
Inside IR35 means HMRC considers your contract to be one of disguised employment. In practice this means:
- You are typically paid via an umbrella company, which acts as your employer for tax purposes.
- The umbrella deducts employer NI (15% on earnings above £5,000) from your contract rate before calculating your pay.
- You pay income tax and employee NI on the remaining amount under PAYE — exactly like a permanent employee.
- You cannot claim most business expenses, and any umbrella fee is an additional deduction.
Outside IR35 means you are a genuine independent contractor. You:
- Operate through your own limited company, retaining full control over how you extract income.
- Can take a small director's salary (typically up to the personal allowance) and pay the remainder as dividends, which are taxed at lower rates.
- Pay corporation tax on company profits (19% for profits up to £50,000, rising to 25% above £250,000).
- Can claim legitimate business expenses (accountancy, professional indemnity insurance, equipment, etc.) against your company's profits.
How Inside IR35 Tax Works — Step by Step
- Start with your gross contract value — your day rate multiplied by your working days per year.
- Deduct umbrella fees — your umbrella company charges a monthly admin fee, typically £100–£200/month, deducted from your contract income.
- Deduct employer NI — the umbrella deducts 15% employer NI on earnings above £5,000. This cost, which a normal employer would absorb, is deducted from your contract rate.
- Apply PAYE — the remaining amount is your gross salary. Income tax and employee NI are calculated using standard PAYE rules on this figure.
- Your take-home is what remains after all deductions — noticeably lower than for a permanent employee at the equivalent salary because you have absorbed the employer NI cost.
How Outside IR35 Tax Works — Step by Step
- Company receives revenue — your limited company invoices the client at your day rate.
- Deduct business expenses — legitimate expenses (accountancy, insurance, IT equipment, etc.) reduce your company's taxable profit.
- Pay a small director's salary — typically £12,570 (the personal allowance). This is a company cost that further reduces profits. Employer NI is payable on the band above £5,000.
- Pay corporation tax — the company pays tax on remaining profits at 19–25%.
- Extract dividends — after-tax profits are paid out as dividends. You receive a £500 dividend allowance tax-free, then pay dividend tax at 10.75% (basic), 35.75% (higher), or 39.35% (additional rate).
- Your take-home is the net salary plus net dividends — typically significantly higher than inside IR35 at the same day rate.