What an umbrella company is — and what you're actually paying for
An umbrella company is a business that employs contractors who work on short-term assignments through recruitment agencies. Instead of running your own limited company, you become an employee of the umbrella. The agency pays your assignment income to the umbrella, the umbrella deducts the costs of employing you, and what remains is paid to you through PAYE — the same payroll system used for any salaried job. You get a payslip, statutory holiday pay, sick pay, a workplace pension and continuity of employment across assignments, without the administrative weight of company accounts.
The catch is that the assignment rate is quoted gross of employer costs. Before any of it reaches your PAYE wage, the umbrella has to pay employer National Insurance, the apprenticeship levy, and take its own fee. Understanding that chain is the difference between feeling cheated by your first payslip and reading it like an accountant.
How the weekly margin works
The margin is the umbrella's fee for employing you and running your payroll. It is charged per week — usually somewhere between £15 and £35 — and it applies every week you are paid, regardless of how many days you worked that week. A £20/week margin is about £1,040 a year of gross fees; a £30/week margin is about £1,560. Because the margin comes out of your assignment income before tax, the real cost to you is not the headline fee but its value after the income tax and National Insurance you would otherwise have paid on that money. The calculator above does exactly this sum, holding everything else constant so the margin is the only thing moving.
Why the margin is the main thing that differs between compliant umbrellas
Here is the insight most comparison sites bury: between two compliant umbrella companies, your take-home is almost identical bar the margin. Employer National Insurance is set by HMRC at 15% above a £5,000 threshold. The apprenticeship levy is 0.5%. Holiday pay is a statutory 12.07% accrual. Income tax bands and the PAYE National Insurance you pay as an employee are the same wherever you are employed. None of these are things a provider can change to win your business. The only lever a compliant umbrella controls is its weekly margin — so once you have entered your rate, days and pension, the difference between one umbrella and the next is simply the post-tax value of the difference in their margins. A provider charging £35/week is not giving you anything a £20/week provider isn't; it is keeping more of your money.
That is also why a slick "take-home illustration" from a sales team is rarely worth comparing line by line — if both are compliant, the numbers can only differ by the margin (and any arithmetic sleight-of-hand). If you also want to model the umbrella route against running a limited company inside or outside IR35, use our contractor take-home calculator, which puts all three side by side.
What else to compare beyond the headline margin
Margin is the financial differentiator, but a handful of service factors are worth weighing before you sign:
- Same-day or faster payments. Some umbrellas process your pay the day they receive cleared funds from the agency; others run a weekly cycle. When cash flow is tight, the timing can matter more than a couple of pounds of margin.
- Pension pass-through via salary sacrifice. A good umbrella will let you divert pension contributions through salary sacrifice, which saves both income tax and National Insurance, and pass the employer NI saving back into your pot. Not all do — confirm it, because it is worth far more than the margin difference.
- Insurance cover. Check that the umbrella provides employer's liability, public liability and professional indemnity insurance as standard, since many agencies require it and buying it yourself is expensive.
- Accreditation. Membership of an industry body with an audited compliance standard is a reasonable proxy for "this provider runs everything properly through PAYE."
A warning about "too good to be true" umbrellas
If an umbrella promises 80–90% take-home, or describes paying you a small taxable salary topped up with a tax-free "loan", "grant", "annuity", "capital advance" or anything routed through an offshore company, walk away. These are disguised remuneration tax-avoidance schemes. They work by dressing up your earnings as something that isn't pay, so less tax appears to be due now — but HMRC does not accept the dressing-up, and when the scheme unwinds it pursues you, the worker, for the unpaid tax, often with interest and years later. The short-term gain is never worth it. HMRC publishes clear guidance on how to spot and avoid these arrangements: disguised remuneration tax-avoidance schemes. A compliant umbrella runs everything through PAYE and shows employer NI, the levy and your margin plainly on your payslip — if you can't see those deductions, that is the red flag.