The Residual Rate: Auditing What a UK Contract Really Pays After IR35 and Umbrella Costs

A recruiter's message arrives with a headline number: £500 a day, outside IR35, immediate start. It reads like a salary in disguise. It is not. Between that figure and the balance shown on your banking app sits a chain of deductions — some statutory, some commercial, and at least one that ought to be questioned on sight. Understanding that chain is the difference between a contract that genuinely improves your position and one that quietly erodes it.

The document that governs everything: the Status Determination Statement

Before discussing money, establish the tax status of the engagement. For medium and large end clients, the responsibility for determining employment status for tax sits with the client, and that determination must be communicated in a Status Determination Statement. The SDS is not a courtesy note. It is the document that tells you whether the fee payer will operate PAYE on your pay or whether you will account for tax through your own company.

Read it for two things. First, the conclusion — inside or outside IR35. Second, and more importantly, the reasoning. A compliant SDS explains which factors were weighed: supervision, direction and control; the right to send a substitute; financial risk; and the degree of mutuality of obligation. A statement that simply asserts a conclusion without reasoning is a warning sign, and you are entitled to challenge it through the client's disagreement process.

Small clients are exempt from the rules, which shifts the determination back to your own company. That is not a licence to self-declare convenience. If HMRC later disagrees, the liability follows you.

Assignment rate, pay rate and the gap between them

Most contractors conflate two figures that are not the same. The assignment rate — sometimes called the limited company rate or the gross contract rate — is what the end client pays for the work. The pay rate is what reaches you as taxable pay.

The difference is not profit. It is the cost of employing a human being, and under an umbrella arrangement the umbrella company bears those costs out of the assignment rate. That typically includes:

• Employer National Insurance contributions, charged at 15% on earnings above the secondary threshold.
• The apprenticeship levy, at 0.5% of the pay bill for larger employers.
• Holiday accrual, because as an employee of the umbrella you are entitled to 5.6 weeks of statutory leave.
• Auto-enrolment pension contributions, at minimum statutory levels unless you opt out.
• The umbrella's own margin, usually a modest weekly sum but one that compounds across a long engagement.

Ask the recruiter, in writing, for both numbers: the assignment rate and the expected pay rate. If they can only supply the first, that is not an oversight — it is a negotiating position.

Holiday pay should not be rolled into the rate

A recurring feature of umbrella illustrations is a line labelled 'rolled-up holiday pay', presented as a 12.07% enhancement to your hourly or daily rate. Treat this as a compliance question rather than a perk.

Statutory holiday pay must be paid when holiday is actually taken. Building an allowance into every payslip and calling it holiday pay does not satisfy that requirement, and it leaves you in the unsatisfactory position of funding your own leave from money you have already been taxed on. A compliant umbrella will accrue holiday pay separately, show the accrual, and release it when you book time off.

When you compare offers, therefore, compare like with like. A rate that includes rolled-up holiday pay is roughly 12% smaller than it appears.

Vetting the umbrella company itself

The umbrella sector has been the subject of sustained regulatory attention, and the compliance environment has tightened considerably. From April 2026, responsibility for unpaid PAYE in umbrella chains can transfer up the supply chain to the recruitment agency, which means reputable agencies now scrutinise their umbrella partners closely. Use that to your advantage.

Practical checks before you sign up:

1. Confirm the umbrella holds its own PAYE scheme reference and that it appears on HMRC's published guidance for workers.
2. Verify membership of a recognised accreditation body. Accreditation is a proxy for good practice, not a guarantee, but its absence is telling.
3. Ask for a written illustration based on the actual assignment rate, showing employer NI, levy, holiday accrual, pension and margin as separate lines.
4. Confirm how expenses are treated and whether any element is being reclassified as salary sacrifice.
5. Establish who your contract of employment is with, and read the notice and termination terms in it.

If an umbrella cannot produce a transparent illustration, the conversation is over.

Building a true take-home comparison

Set out the arithmetic on one page. Work through the assignment rate, strip the employer costs, arrive at taxable pay, then apply income tax and employee National Insurance. Use a realistic number of billable days — 220 is a common planning assumption for a full-time contractor, not 260 — and account for gaps between engagements.

As an illustration, an assignment rate of £500 per day across five days produces a weekly assignment value of £2,500. After a typical umbrella margin, employer NI, levy and holiday accrual, taxable pay lands materially below that — often in the region of £1,700 to £1,800 for the working element of the week, with holiday pay held separately. Net of income tax and employee NI, the effective daily take-home frequently settles somewhere between £300 and £330 depending on tax code and pension choices. The precise figures will vary; the shape of the calculation will not.

Then place the permanent alternative beside it. Add the employer pension contribution, which may be worth 5% to 10% of salary. Add paid holiday, sick pay, notice periods and any bonus. A £70,000 salary with a 10% employer pension contribution is a considerably larger package than its headline suggests, and it is not unusual for a contract to look superior on gross terms and merely equivalent once these items are priced in.

The judgement, not just the calculation

The purpose of this exercise is not to prove that contracting is better or worse than employment. It is to make the comparison honest. A day rate is a revenue figure for a business, and once you treat it as such — subtracting the costs of employing yourself, allowing for unworked weeks, and pricing the benefits you are forgoing — the decision becomes a commercial one rather than an emotional one.

Ask for the SDS, ask for the pay rate, ask for the umbrella illustration in writing, and put the numbers side by side before you resign from anything. The headline rate is the beginning of the conversation, never the end of it.

This article offers general information only and does not constitute tax or legal advice. Contractors with complex affairs should consult a regulated adviser.