IR35 Calculator

Work out whether a contract is inside or outside IR35 — and what it pays either way. Answer eight questions about control, substitution and the other status factors, then compare inside-IR35 take-home pay against the simplified limited-company route on your day rate. Free, with nothing to sign up for.

Day rate (£)

What the client pays per day, before tax.

Days per week

Weeks per year

46 weeks leaves about six weeks off; 52 is a full year.

Part 1 — Is this contract inside or outside IR35?

Answer the eight questions about how the work is actually done — not just what the contract says. This is guidance only: HMRC’s CEST tool is the official checker, and HMRC stands by a CEST result given on accurate information.

1. Does the client decide what work you do, and when, where and how you do it?

2. Could you send someone else to do the work instead of you?

3. Must the client offer you work, and must you accept it when it is offered?

4. Do you carry financial risk — paying to put mistakes right, or going unpaid if the work is not done?

5. Are you treated like the client's own staff — a line manager, appraisals, staff meetings, a company email address?

6. Does the client provide the equipment you work with?

7. Do you work for other clients at the same time?

8. Does the client pay you holiday pay, sick pay or a pension?

Private by design: everything is worked out in your browser. Nothing you type here is sent to a server, stored or tracked.

Status check: 0 of 8 questions answered — answer them all to see whether this contract looks inside or outside IR35.

Part 2 — Inside vs outside: what the same contract pays

£115,000.00 contract value a year

£500.00 a day × 5 days a week × 46 weeks a year.

Inside IR35 — deemed employment

Income Tax:: £36,432.00 a year.
Employee National Insurance:: £4,310.60 a year.
Take-home pay:: £74,257.40 a year (64.57% of the contract value).
Employer NI the fee-payer pays on top:: £16,500.00 a year — 15% of the contract value above £5,000. It is not deducted from your pay, but it is part of what the engagement costs the client.

Student loan is not deducted by the deemed employer — you pay it through Self Assessment.

Outside IR35 — limited company (simplified)

Director’s salary:: £12,570.00 a year.
Employer NI on the salary:: £1,135.50 — a one-director company cannot claim the Employment Allowance.
Company profit:: £101,294.50.
Corporation Tax:: £23,093.04.
Dividends:: £78,201.46 — all post-tax profit taken as dividends.
Dividend tax:: £18,353.27 (after the £500 dividend allowance).
Take-home pay:: £72,418.19 a year (62.97% of the contract value).

Inside IR35 pays £1,839.21 a year more on these figures — £74,257.40 inside against £72,418.19 outside. That gap is the tax difference only: it does not count pension contributions, keeping money in the company, or the cost of running a company.

Simplified model: one director, a salary of exactly the Personal Allowance (£12,570), no other income, no expenses, no pension contributions, no VAT, and every pound of post-tax profit taken as dividends in the same tax year. England, Wales and Northern Ireland tax bands, 2026/27 rates. Real companies keep money in the company, pay pension contributions and time dividends — all of which change the answer. This is a starting point, not advice.

Opens your browser's print view with a clean summary of this calculation — choose “Save as PDF” there to keep a copy.

How to use this IR35 calculator

This calculator is part of UK Payroll Calculators, a free hub of UK payroll calculators built on the April 2026 rules — no sign-up, no accounts, and every figure worked out in your browser. It works in two parts. First, answer the eight status questions about how the work is actually done — not just what the contract says — and the calculator shows whether the contract looks inside IR35, outside it, or borderline. Then enter the day rate, days per week and weeks per year, and the calculator compares the take-home pay inside IR35 (taxed as deemed employment) with the simplified limited-company route outside it.

How do you know if a contract is inside IR35?

The off-payroll working rules apply when a worker providing services through their own intermediary — usually a limited company, often called a personal service company — would have been an employee if they had provided the services directly to the client. There is no single test. HMRC looks at the whole picture, and the three factors that carry the most weight are control, substitution and mutuality of obligation: does the client decide what work is done, and when, where and how? Can the worker send someone else instead? And must the client offer work, and must the worker accept it? The other five factors the calculator asks about are financial risk, whether the worker is part of the client's organisation, who provides the equipment, whether the worker has other clients, and whether the client pays employee benefits such as holiday pay, sick pay or a pension. What matters is the reality of the working arrangement, not just the words in the contract — a substitution clause that is never used in practice counts for little.

Who decides the IR35 status?

In most cases the client decides the worker's employment status for tax, and must produce a status determination statement — including the reasons — for the worker and anyone else in the chain. That covers public-sector clients and medium and large private-sector clients. Only where the client is a small business outside the public sector does the worker's own intermediary decide whether the rules apply. The rules apply contract by contract: a worker may have some contracts inside the off-payroll rules and some outside them. If a contract is determined to be inside IR35, the deemed employer — usually the agency, or the client where there is no agency — must deduct Income Tax and employee National Insurance from the fees paid to the worker's company, and must pay employer National Insurance (and the Apprenticeship Levy, where it applies) to HMRC. Umbrella company workers are unlikely to be affected, because they are already employed by the umbrella company.

Inside IR35 vs outside: the tax difference

Take a £500 day rate, 5 days a week, 46 weeks a year — a £115,000.00 contract. Inside IR35, the deemed employer deducts £36,432.00 of Income Tax and £4,310.60 of employee National Insurance, leaving £74,257.40 a year — 64.57% of the contract value. Outside IR35, the simplified limited-company route pays a £12,570.00 salary, then Corporation Tax of £23,093.04 on the £101,294.50 profit and dividend tax of £18,353.27 on the £78,201.46 of dividends, leaving £72,418.19 — £1,839.21 a year less than inside. The fee-payer also pays £16,500.00 of employer National Insurance on top of the contract value inside IR35. The gap is not fixed — it moves with the rate:

Day rate	Contract value	Take-home inside IR35	Take-home outside IR35	Difference
£250.00	£57,500.00	£43,907.40	£44,283.89	+£376.49 (outside wins)
£400.00	£92,000.00	£63,917.40	£61,556.73	−£2,360.67 (inside wins)
£500.00	£115,000.00	£74,257.40	£72,418.19	−£1,839.21 (inside wins)
£600.00	£138,000.00	£84,926.40	£81,552.55	−£3,373.85 (inside wins)
£800.00	£184,000.00	£109,306.40	£98,775.60	−£10,530.80 (inside wins)

Every row is the same shape — 5 days a week, 46 weeks a year. At £250 a day the outside route wins by £376.49 a year; from £400 a day up, inside wins, and the gap widens as the rate rises — because the Personal Allowance tapers away, Corporation Tax moves from the 19% small profits rate towards the 25% main rate, and more of the dividends fall into the 35.75% higher-rate band. The comparison is tax only: it does not count pension contributions, keeping money in the company, or the cost of running a company, all of which can change the answer in real life.

Rules used by this calculator

Figure	How it is worked out
Status check	Eight factors — control, substitution, mutuality of obligation, financial risk, integration, equipment, other clients, employee benefits. 0–2 answers pointing to employment: likely outside; 3–5: borderline; 6–8: likely inside. Guidance only — not a determination.
Inside IR35	Income Tax and employee National Insurance on the full contract value, at the 2026/27 rates (Personal Allowance £12,570, tapered above £100,000; 20% / 40% / 45%; employee NI 8% to £50,270, 2% above). Student loan is not deducted.
Employer NI (fee-payer)	15% of the contract value above the £5,000 Secondary Threshold, paid on top by the deemed employer — not deducted from the worker's pay.
Outside IR35 (simplified)	Salary of exactly the Personal Allowance (£12,570); employer NI 15% above £5,000 in full — a one-director company cannot claim the Employment Allowance. Profit = contract value − salary − employer NI.
Corporation Tax	19% on profits up to £50,000, 25% on profits over £250,000, Marginal Relief between the two.
Dividend tax (2026/27)	£500 dividend allowance, then 10.75% at the basic rate, 35.75% at the higher rate, 39.35% at the additional rate. Dividends are the top slice — the salary is taxed first, and the Personal Allowance covers dividend income that falls within it.
Outside take-home	Salary (less any Income Tax on it once the allowance tapers) + dividends − dividend tax. All post-tax profit is taken as dividends in the same tax year; no expenses, pension or VAT are counted.

The rules follow GOV.UK's Understanding off-payroll working (IR35), Check employment status for tax (CEST), Corporation Tax rates, Tax on dividends and Claim Employment Allowance.

Rules and rates checked against GOV.UK on 9 November 2026. This calculator is guidance only and is not HMRC's CEST tool — for a determination, run CEST on the real contract. Tax bands are for England, Wales and Northern Ireland; Scotland sets its own Income Tax bands.

Frequently asked questions

How do I know if my contract is inside IR35?

There is no single test — HMRC looks at the whole picture, and the three factors that carry the most weight are control (does the client decide what, when, where and how the work is done?), substitution (can you send someone else instead?) and mutuality of obligation (must the client offer work and must you accept it?). The other factors are financial risk, whether you are part of the client's organisation, who provides the equipment, whether you have other clients, and whether the client pays you employee benefits. Answer the eight questions above and the calculator shows which way your contract points — then run HMRC's CEST tool on the real contract for the official view.

What is the difference between inside and outside IR35 take-home pay?

On a £500 day rate, 5 days a week for 46 weeks — a £115,000.00 contract — inside IR35 the deemed employer deducts £36,432.00 of Income Tax and £4,310.60 of employee National Insurance, leaving £74,257.40 a year. Outside IR35, the simplified limited-company route (a £12,570 salary plus all post-tax profit as dividends) leaves £72,418.19 — £1,839.21 a year less on these figures. At a £250 day rate the answer flips: outside pays £376.49 a year more. The gap depends on the rate, because the Personal Allowance taper, Corporation Tax and dividend tax all bite harder as income rises.

Who decides whether a contract is inside IR35?

In most cases the client decides, and must give the worker a status determination statement with the reasons. That covers public-sector clients and medium and large private-sector clients. Only where the client is a small private-sector business does the worker's own intermediary (usually their limited company) decide. The rules apply contract by contract — the same worker can have one contract inside IR35 and another outside it.

What tax is deducted if I am inside IR35?

The deemed employer — usually the agency or the client — must deduct Income Tax and employee National Insurance from the fees paid to your company, and must pay employer National Insurance on top (£16,500.00 a year on a £115,000.00 contract). The Apprenticeship Levy applies too where the fee-payer's pay bill is large enough. One thing is not deducted: student or postgraduate loan repayments — you pay those yourself through Self Assessment.

Is this IR35 calculator the same as HMRC's CEST tool?

No. HMRC's Check Employment Status for Tax (CEST) tool is the official checker, and HMRC will stand by a CEST result as long as the information given was accurate and follows its guidance — a CEST result can even be used as a status determination statement. This calculator is guidance only: it asks the same eight factors CEST weighs, so you can see which way a contract points and what the tax difference is, before you run the official tool on the real contract.