How it’s worked out
Your contract value is your day rate multiplied by the days you work each week and the weeks you work each year. Most contractors bill 44 to 46 weeks once holidays, bank holidays and the gaps between contracts are taken out, so 46 is a sensible starting point.
Through a limited company, your company receives the full contract value. It pays your running costs, a director's salary of £12,570 (the personal allowance, so no income tax) and employer National Insurance at 15% on salary above £5,000. What's left is profit, which pays corporation tax at 19% to 25% with marginal relief in between. Everything after corporation tax is paid to you as dividends, taxed at 10.75%, 35.75% or 39.35% after the £500 dividend allowance.
Through an umbrella, the umbrella company receives the contract value, takes its margin, and then pays employer National Insurance and the 0.5% apprenticeship levy out of what's left before your gross salary is set. You then pay income tax and employee National Insurance through PAYE like any employee. That's why umbrella take-home is usually lower at the same day rate: employer costs come out of your rate rather than on top of it.
The calculator uses 2026/27 rates for England, Wales and Northern Ireland. It doesn't include student loan repayments, pension contributions in the limited company, or Scottish income tax bands.
Questions
Is a limited company always better than an umbrella?
Not always. Outside IR35, a limited company usually leaves you more, but it comes with accountancy costs, admin and responsibility for IR35 status. Inside IR35 most contractors work through an umbrella or the client's payroll.
Why does the umbrella deduct employer National Insurance from my rate?
The umbrella is your employer, and the agency rate it receives has to cover all employment costs. Employer NI and the apprenticeship levy are paid from the assignment rate before your gross salary is worked out.
How many weeks should I enter?
Use the weeks you expect to bill. 46 weeks allows for 25 days' holiday plus bank holidays. If you expect gaps between contracts, use a lower number.
These figures are estimates for guidance only and aren’t financial or tax advice. Speak to an accountant before making decisions.