IR35 Status Checker 2025 — Are You Inside or Outside IR35?
A complete guide to the IR35 rules, the 3 key tests, the real cost difference, and what to do after you check your IR35 status.
You've just landed a new contract. The day rate looks good. But then your client mentions IR35 — and suddenly everything feels uncertain. IR35 is the UK tax legislation designed to identify contractors who HMRC considers "disguised employees" — people working through a limited company who would otherwise be classed as employees if that company didn't exist. Use the free IR35 status checker above for an instant assessment. This guide explains exactly how the rules work in 2025, what your result means, and what to do next.
What Is IR35 — And Why Does It Matter So Much?
IR35 was introduced in 2000 to tackle what HMRC called "disguised employment." If you work through a limited company but your arrangement looks and feels like employment, HMRC wants you to pay tax like an employee. The financial consequences are significant — the difference between inside and outside IR35 at typical contractor rates is £8,000–£15,000+ per year.
⚠️ Inside IR35
- → Taxed as an employee via PAYE
- → Employer NI at 15% absorbed from your rate
- → No tax-efficient dividend strategy
- → Lose £8,000–£15,000+ per year typically
✓ Outside IR35
- → Operate as genuine limited company
- → Pay yourself salary + dividends
- → Claim legitimate business expenses
- → Keep 70–80% of your gross day rate
The 3 Key IR35 Tests HMRC Uses to Judge Your Status
1. Control
Does your client control what you do, how you do it, and when? If yes, that looks like employment. A genuine contractor decides their own working methods and delivers agreed outputs without being micromanaged on process.
Example: If your client requires you in the office 9–5 and dictates exactly how to write every line of code, that's a red flag. If you decide your own schedule and methodology and deliver agreed outcomes, that supports outside IR35.
2. Substitution
Can you send a qualified colleague in your place to do the work? A genuine business can substitute — an employee cannot. The right doesn't need to be exercised in practice, but it must be genuine and the client must realistically accept it.
Example: If your contract allows a suitably qualified substitute and the client would genuinely accept them, that's a strong outside IR35 indicator. If the client insists on your personal service and would reject any substitute, that points inside IR35.
3. Mutuality of Obligation (MOO)
Is the client obliged to offer you work — and are you obliged to accept it? High mutuality of obligation is a hallmark of employment. A genuine contractor has a defined scope: deliver a project, then you're done. Notably, HMRC's own CEST tool controversially omits MOO from its assessment — a key reason tax professionals consider it incomplete.
Example: If you're contracted to deliver a specific system and when done you're finished — that's low MOO. If you're expected to be available indefinitely and always roll onto the next project, that's high MOO.
| IR35 Test | Outside IR35 Signal | Inside IR35 Signal |
|---|---|---|
| Control | You choose how & when to work | Client dictates methods & hours |
| Substitution | Can send a qualified substitute | Must deliver the work personally |
| Mutuality of Obligation | No obligation to accept further work | Expected to always be available |
Other Factors HMRC Also Considers
Financial Risk
Do you risk your own money if a project goes wrong? Genuine businesses bear financial risk — fixing faults in your own time at your own cost, without extra pay. Employees don't carry this risk.
Part and Parcel
Are you treated like a permanent employee — given a company desk, email address, appearing on their org chart, attending company events? This level of integration suggests employment status rather than genuine contracting.
Right of Substitution in the Contract
Your written contract matters — but HMRC looks at the reality, not just the paper. A substitution clause that would never be used in practice provides very limited protection under scrutiny.
Provision of Equipment
Do you use your own laptop, software, and tools of the trade? Genuine contractors typically do. Being issued company devices and a security pass on day one looks employee-like to HMRC.
Inside vs Outside IR35 — The Real Cost Difference
A worked example for a contractor billing £500/day (~£110,000/year at 220 days) under 2025/26 rates:
| Scenario | Annual Tax Paid | Estimated Take-Home |
|---|---|---|
| Outside IR35 (Ltd Co) | ~£28,000 | ~£82,000 |
| Inside IR35 (PAYE) | ~£43,000 | ~£67,000 |
| Difference | £15,000 more tax | £15,000 less take-home |
This is why IR35 status isn't just a compliance issue — it's a financial one. Getting it wrong costs you thousands every year.
Public Sector vs Private Sector IR35 Rules
The 2017 off-payroll working reform moved IR35 status responsibility from contractors to end clients in the public sector. From April 2021, the same change extended to medium/large private sector companies. Your end client now determines your status and must issue a Status Determination Statement (SDS) — a written notice of their IR35 decision with their reasoning. The exception is small companies (under £10.2m turnover, under £5.1m balance sheet, or fewer than 50 employees) — contractors working for small clients still determine their own IR35 status.
| Sector / Client Type | Who Decides IR35 Status? |
|---|---|
| Public sector (NHS, councils, govt) | End client (since 2017) |
| Private sector — medium/large company | End client (since April 2021) |
| Private sector — small company | Contractor determines own status |
What Is HMRC's CEST Tool — And Is It Reliable?
CEST (Check Employment Status for Tax) is HMRC's own online IR35 checker. HMRC says they'll stand behind CEST results if you answer accurately and honestly. But CEST is controversial — it doesn't properly account for Mutuality of Obligation, one of the three cornerstone IR35 tests, and returns "unable to determine" for a significant proportion of cases.
CEST is worth running as a data point — but it shouldn't be your only check. Use it alongside this tool, review your actual working practices, and for any contract with significant money at stake, get a formal review from a specialist such as Qdos or IR35 Shield. A contractor accountant who specialises in IR35 is worth their weight in gold if your status isn't clear-cut.
What to Do After You Get Your Result
If You're Likely Outside IR35
Don't get complacent. Ensure your written contract reflects genuine outside IR35 working practices, keep records of how you actually work (own equipment, flexible hours, no client integration), and for contracts above £500/day, a professional contract review from Qdos or IR35 Shield is money very well spent. It provides documented protection should HMRC ever enquire.
If You're Borderline
Take this seriously. Borderline means real risk — some factors support outside IR35 while others don't. Get a professional contract review immediately and examine whether your actual working practices match what the contract says. HMRC tends to find their cases exactly at the gap between paper and reality.
If You're Likely Inside IR35
Don't panic — many contractors work legitimately inside IR35. Your options: move to an umbrella company (which handles all PAYE administration cleanly), renegotiate your day rate for an "IR35 rate uplift" to account for the higher tax, or seek outside IR35 contracts instead. Speak to a contractor accountant who can map out the real financial impact at your rate.
Frequently Asked Questions
What does inside IR35 actually mean?
Inside IR35 means HMRC considers your working arrangement equivalent to employment. In practice, the fee-payer (usually the agency or direct client) must deduct income tax and National Insurance before paying you, just like an employer. You lose the ability to take dividends tax-efficiently and typically take home significantly less than an outside IR35 contractor on the same day rate.
Can I appeal an IR35 determination from my client?
Yes. If your end client issues a Status Determination Statement that you believe is incorrect, you can use their formal disagreement process to challenge it. The client must respond within 45 days with either a revised determination or a detailed explanation for maintaining their original decision. If you're still unhappy, you can escalate to HMRC. This right applies to medium/large private sector clients and public sector bodies — not small companies where you determine your own status.
Does IR35 apply if I work through an umbrella company?
No — IR35 doesn't apply to umbrella company workers. Umbrella companies employ you directly and run full PAYE payroll as standard, so you're taxed as an employee from day one. There's no IR35 question because you're not operating through your own limited company. Many contractors whose contracts fall inside IR35 choose umbrella companies as the simplest, most compliant route.
What is a Status Determination Statement (SDS)?
A Status Determination Statement is a written document that your end client is legally required to give you when they assess your IR35 status — if they're a medium/large private sector company or public sector body. It must clearly state their conclusion (inside or outside IR35) and the reasoning behind it. Without a valid SDS, the IR35 liability shifts back to the end client. Always request your SDS and check whether the reasoning genuinely reflects your working arrangement.
Can I work both inside and outside IR35 at the same time?
Yes — IR35 status is assessed per contract, not per person. If you have two simultaneous contracts, each is treated completely separately for tax purposes. Your inside IR35 income is taxed as employment income; your outside IR35 income goes through your limited company as normal. Keep meticulous records and ensure each contract has clear, separate terms that accurately reflect how each engagement actually works.
How often should I check my IR35 status?
Check your status any time something materially changes: when you start a new contract, when an existing contract is renewed or extended, when your working practices shift, or when a new tax year brings updated HMRC rules. A contract that was clearly outside IR35 twelve months ago might look different today if the client has gradually increased their control or integrated you more into their team. Use this checker as a regular health check, not a one-time exercise.
Important Disclaimer
This IR35 status checker is a free guidance tool only — it is not a formal HMRC determination and does not constitute legal or tax advice. Results are based on general IR35 principles and weighted scoring built from HMRC guidance and employment case law. Your actual IR35 status depends on the specific facts of your contract and your working practices. For any contract where significant money is at stake, always consult a specialist contractor accountant or an IR35 review service such as Qdos, IR35 Shield, or Kingsbridge before making decisions.
IR35 is complex — but it's knowable. The three key tests — Control, Substitution, and Mutuality of Obligation — give you a clear framework for assessing any contract. Use the checker at the top of this page as your starting point, understand what your result means, and take the right next step based on what you find. With potentially £15,000 or more per year at stake, this is one compliance question absolutely worth getting right.