IR35 / Off-Payroll Calculator
Compare a contract as inside IR35 PAYE income with an outside IR35 limited company route. This calculator does not decide your status; it shows the money difference once a contract is treated one way or the other.
Compare inside and outside IR35
Enter the contract value, then choose how employer costs are handled for the inside-IR35 estimate.
Choose whether employer NI/levy sit on top of the rate or reduce the contract pot.
Used before this contract income for tax-band estimates.
Comparison type
Inside vs outside
A take-home comparison after status has been decided elsewhere.
Employer NI estimate
15%
Applied above the secondary threshold for the employer-cost view.
Outside extraction
Salary + dividends
A simple PSC model after company expenses and Corporation Tax.
What this IR35 calculator is actually for
IR35 is often discussed as if it is just a tax-rate switch. It is not. The first question is status: would the worker be an employee for tax if the personal service company did not sit in the middle? That depends on the contract and working practices, including control, substitution, mutuality of obligation, financial risk and how the engagement actually runs day to day.
This calculator starts after that status question. It compares the money if the engagement is treated as inside IR35, where PAYE tax and employee National Insurance apply, against an outside IR35 company route where the company pays expenses, salary, Corporation Tax and dividends. That is useful when deciding whether a day rate is worth accepting, or whether an inside rate needs renegotiating.
The result is not a legal conclusion, a status determination statement, or a substitute for the HMRC CEST tool. It is a planning estimate. The more complex your company, pension contributions, other income, associated companies, VAT position or expenses are, the more likely you need a proper accountant's model.
| Route | What the calculator models |
|---|---|
| Inside IR35 | PAYE Income Tax and employee NI on deemed employment income |
| Employer-cost pressure | Employer NI and optional Apprenticeship Levy |
| Outside IR35 | PSC expenses, salary, employer NI, Corporation Tax and dividends |
| Not modelled | Status decision, VAT, pension strategy, expenses compliance, benefits or student loans |
How this IR35 calculator works
Inputs used
- Tax year, because PAYE, employer NI, Corporation Tax and dividend rates can change.
- Day rate and billable days, used to estimate annual contract revenue.
- PAYE tax region for the inside-IR35 employment-income estimate.
- Whether employer NI and optional Apprenticeship Levy are shown as costs on top or deducted from the contract pot.
- Outside-IR35 company expenses, director salary and Employment Allowance assumption.
Calculation method
- Estimate annual contract value from day rate multiplied by billable days.
- Inside IR35: calculate PAYE Income Tax and employee National Insurance on the deemed employment income.
- If employer costs are deducted from the contract pot, solve for a lower deemed gross pay after employer NI and optional levy.
- Outside IR35: subtract company expenses, director salary and employer NI, then calculate Corporation Tax on remaining company profit.
- Treat post-Corporation Tax profit as dividends and estimate dividend tax after the director salary and other income.
- Compare inside-IR35 net income with outside-IR35 salary-plus-dividend net income.
Assumptions
- The calculator assumes the contract status has already been decided. Use HMRC CEST, the client status determination process, or professional advice for status.
- Outside IR35 assumes a simple personal service company with no VAT, no associated companies, no pension contributions and dividends paid from available post-tax profit.
- Scottish selection affects earned PAYE-style income. Dividend tax is still estimated using UK dividend rates, with simplified band allocation.
- Corporation Tax marginal relief is estimated using standard GBP 50,000 and GBP 250,000 limits and assumes no associated-company adjustment.
What this does not cover
- It does not decide IR35 status, employment law status, substitution rights, supervision/control, mutuality of obligation or whether a Status Determination Statement is valid.
- It does not include pension contributions, student loans, umbrella company margin, holiday pay accrual, VAT, Flat Rate Scheme VAT, benefits in kind, or expenses compliance.
- It does not replace the Director Salary + Dividend Calculator, Corporation Tax Calculator, or True Cost of an Employee Calculator for deeper checks.
Worked example: why the advertised rate matters
Say a contractor is offered GBP 600 a day for 220 days, giving GBP 132,000 annual contract value. If the role is outside IR35, the company might pay a small salary, claim genuine company expenses, pay Corporation Tax on the remaining profit, and distribute the rest as dividends.
If the same engagement is inside IR35, the route changes. PAYE Income Tax and employee National Insurance apply to the deemed employment income. Employer National Insurance is not employee tax, but if the market rate has been reduced to reflect employer costs, the worker still feels it through a lower day rate or a lower gross pot.
This is why comparing only the headline day rate is dangerous. A GBP 600 outside rate and a GBP 600 inside rate are not economically identical if employer costs, umbrella margin, holiday pay or pension handling sit inside the same pot. The calculator separates those moving parts so the negotiation is easier to see.
Status checks this page cannot do
The status decision is not made by the calculator. For medium and large private-sector clients, and public sector clients, the client normally decides whether the off-payroll rules apply and gives a Status Determination Statement. Small private-sector clients can leave the responsibility with the worker's company under the older IR35 route.
The practical evidence matters as much as the written contract. If the contract says you can send a substitute but the client would never accept one, that is not a detail to ignore. If the client controls your hours, methods, location and tasks like an employee, that is also important.
Use this page once you are comparing rates or planning cash flow. Use CEST, a proper contract review, or professional advice when you need to decide status.
Inside IR35, outside IR35, umbrella: what changes?
Inside IR35
Taxed broadly like employment for the engagement, with PAYE and employee NI on the deemed direct payment.
Outside IR35
The company route can use genuine expenses, salary, Corporation Tax and dividends, subject to company tax rules.
Umbrella
Often PAYE employment through an umbrella company, with extra details such as margin and holiday pay handling.
An inside IR35 assignment and an umbrella assignment can feel similar because both usually produce PAYE-style payslips. They are not always identical in how the assignment rate is broken down. Before accepting a contract, ask for a key information document or illustration that shows gross pay, employer costs, employee deductions, holiday pay, pension, umbrella margin and net pay.
Common mistakes with IR35 calculators
Using a take-home result as a status answer
A large tax difference does not prove a contract is outside IR35. Status is about the legal and practical relationship.
Ignoring employer costs in the rate
Employer NI should not be deducted as employee tax, but the advertised rate may already be lower because those costs exist.
Overstating outside-IR35 dividends
Dividends come from post-Corporation Tax profit. Company costs and salary come first.
Forgetting other income
Other salary, pensions, dividends or rental income can push contract income into higher tax bands.
IR35 calculator FAQs
Does this calculator tell me if I am inside IR35?
Is employer National Insurance deducted from my pay?
Are student loans deducted from inside IR35 payments?
Why is outside IR35 not just the same as taking dividends?
Should I accept a lower inside IR35 rate?
Official sources
Last verified: May 9 2026. Calculations are estimates based on the published rules and assumptions shown on this page.
- GOV.UK understand off-payroll working rules - off-payroll scope, contract-by-contract status, and deemed employer responsibilities
- GOV.UK Check Employment Status for Tax - official HMRC CEST tool for status checks
- GOV.UK fee-payer responsibilities under off-payroll working - PAYE, employee National Insurance, employer National Insurance and Apprenticeship Levy treatment
- GOV.UK employer rates and thresholds 2026 to 2027 - employee and employer National Insurance thresholds and rates
- GOV.UK Income Tax rates and allowances - Personal Allowance and UK tax bands used for PAYE estimates
- GOV.UK Corporation Tax rates - small profits, main rate and marginal relief reference for limited company estimates
- GOV.UK tax on dividends - dividend allowance and dividend tax rates