What is IR35 and who does it affect?

IR35 (off-payroll working rules) affects contractors who provide services through an intermediary (e.g. a personal service company). If caught by IR35, income is treated as employment income and subject to PAYE tax and NICs.

What are the three key tests for IR35?

The three key tests are: (1) Control — does the client control how, when, and where work is done? (2) Substitution — can the contractor send a substitute? (3) Mutuality of obligation — must the client offer work and the contractor accept it? All three are assessed holistically.

UK IR35 Contractor Status Check

Formula Definitions

The UK IR35 Contractor Status Check works by applying a well-defined formula to the values you enter. Understanding the formula behind the calculation helps you interpret the result and check that your inputs are correct. Below we break down the key components that drive the IR35 Status Check.

The core formula used by this calculator is:

Result = f(principal, rate, time, jurisdiction)

Each variable in the formula has a specific meaning:

principal — Initial amount, income, or base value entered into the IR35 Status Check.
rate — Interest rate, tax rate, return rate, or growth rate applied per period.
time — Number of periods (years, months, or days) over which the calculation runs.
jurisdiction — Country, tax year, filing status, or regional rules that adjust the calculation.
Result — Computed amount: total, liability, return, repayment, or present/future value.

Note: Financial results are estimates and depend on the accuracy of the inputs and applicable rules.

How to Use This Calculator

Enter your financial figures. Enter income, principal, interest rate, tax year, or relevant financial parameters into the UK IR35 Contractor Status Check.
Adjust regional settings. Select your country, tax jurisdiction, filing status, or applicable tax year and rates.
Calculate your result. Press Calculate to compute the financial result, tax liability, return, or repayment amount.
Review the breakdown. Review the detailed breakdown including totals, effective rates, interest components, and applicable tax implications.

Glossary and Definitions

Principal: The initial amount of money on which interest, returns, or tax liabilities are calculated.
Interest rate: The percentage charged or earned per period on the principal, expressed as an annual rate unless stated otherwise.
Compounding: The process by which interest is added to the principal so that subsequent interest is earned on the combined amount.
Present value: The current worth of a future sum, discounted at a given rate to account for the time value of money.
IR35 check: A key concept referenced by the IR35 Status Check: Assess whether a UK contractor engagement falls inside or outside IR35 (off-payroll working rules). Based on HMRC CEST criteria including control, substitution, and mutuality of obligation.
Off-payroll working: A key concept referenced by the IR35 Status Check: Assess whether a UK contractor engagement falls inside or outside IR35 (off-payroll working rules). Based on HMRC CEST criteria including control, substitution, and mutuality of obligation.
Contractor status: A key concept referenced by the IR35 Status Check: Assess whether a UK contractor engagement falls inside or outside IR35 (off-payroll working rules). Based on HMRC CEST criteria including control, substitution, and mutuality of obligation.
HMRC CEST: A key concept referenced by the IR35 Status Check: Assess whether a UK contractor engagement falls inside or outside IR35 (off-payroll working rules). Based on HMRC CEST criteria including control, substitution, and mutuality of obligation.

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