IR35 Take-Home Pay Calculator UK 2025/26 — Contractor vs Employed
Find out the real difference between working inside and outside IR35. Our 2025/26 calculator models both scenarios side-by-side: limited company optimised structure versus deemed employee PAYE treatment, so you can make an informed decision about your contracting arrangements.
What Is IR35? The Off-Payroll Working Rules Explained
IR35 — formally known as the off-payroll working rules — is tax legislation introduced in 2000 to address what HMRC calls "disguised employment." The rules target contractors who work through their own Personal Service Company (PSC) or limited company but whose working arrangements are, in substance, equivalent to direct employment with the end client.
If a contractor is deemed to be inside IR35, the income they receive through their limited company is treated as employment income for tax purposes. This means paying income tax via PAYE and National Insurance Contributions (NICs) at employee and employer rates, rather than benefiting from the more tax-efficient combination of salary and dividends available to genuine owner-managed businesses.
The Legislative Framework: Chapter 8 vs Chapter 10 ITEPA 2003
IR35 operates through two chapters of the Income Tax (Earnings and Pensions) Act 2003:
| Chapter | Applies To | Who Determines Status | Who Bears Tax Risk |
|---|---|---|---|
| Chapter 8 ITEPA 2003 | Small private sector clients (pre-April 2021 rules) | The contractor's own PSC/limited company | The contractor |
| Chapter 10 ITEPA 2003 | Medium/large private sector and all public sector clients | The end client (engager) | The fee-payer (usually agency or client) |
Since April 2021, the off-payroll working reforms (originally introduced for the public sector in April 2017) were extended to the private sector. Medium and large companies — those meeting at least two of: 50+ employees, £10.2m+ turnover, £5.1m+ balance sheet — must now assess and declare IR35 status for every contractor engagement.
Status Determination Statements (SDS)
When a medium or large client engages a contractor through a PSC, they must issue a Status Determination Statement (SDS) setting out their IR35 determination and the reasons for it. The SDS must be provided to the contractor and the fee-payer (usually the agency) before payments are made. Failure to issue a valid SDS means the client becomes the liable party for any underpaid tax.
Contractors have the right to formally dispute an SDS. The client must respond within 45 days with either a new determination or written reasons for maintaining their original position. This is known as the Client-Led Disagreement Process. If unresolved, HMRC remains the final arbitrator.
The Three Key Employment Status Tests
IR35 status is determined using the same common law tests as employment status. The three most important factors are:
- Mutuality of Obligation (MOO): Is there an obligation on the client to offer work, and on the contractor to accept it? High MOO points towards employment. Genuine contractors should be free to decline work between projects.
- Control: Does the client control how, when, and where the work is performed? Employees are typically told how to do their job; contractors determine their own method. High client control is a strong indicator of employment.
- Right of Substitution: Can the contractor send a substitute to perform the work? A genuine, unfettered right to substitute is one of the strongest indicators of self-employment. If the contract requires personal service only, this points towards employment.
HMRC's CEST (Check Employment Status for Tax) tool is the official online questionnaire for assessing IR35 status. However, it has been criticised by professional bodies (including the Chartered Institute of Taxation) for failing to adequately address mutuality of obligation in all cases. Many IR35 specialists recommend supplementing CEST with a detailed contract and working practices review.
Following the House of Lords Economic Affairs Committee's 2020 report and subsequent HMRC guidance, clients cannot apply a blanket "all contractors are inside IR35" policy. Each engagement must be assessed individually on its own facts. Blanket determinations expose clients to legal challenge and potential employment law claims.
Outside IR35 — How the Limited Company Structure Works
When working outside IR35, contractors typically operate via a Personal Service Company (limited company), extracting income in the most tax-efficient way:
- Director's Salary: Usually set at the Personal Allowance level (£12,570 in 2025/26) or the NI Secondary Threshold to minimise NI liability while maintaining NI contribution record. For 2025/26, the optimal salary is typically £12,570 — above the Primary Threshold, meaning the director builds state pension entitlement.
- Corporation Tax: Company profits are subject to Corporation Tax at 19% (small profits rate on profits up to £50,000) or 25% (main rate on profits over £250,000), with marginal relief between these thresholds. The effective rate at £100,000 profit is approximately 26.5%.
- Dividend Allowance: For 2025/26, the dividend allowance remains at £500. Dividends within this amount are tax-free.
- Dividend Tax Rates (2025/26): Basic rate 8.75%, Higher rate 33.75%, Additional rate 39.35%.
Inside IR35 — The Deemed Payment Calculation
When inside IR35, the fee-payer (usually the agency or client) deducts PAYE income tax and both employee and employer NICs before paying the contractor's PSC. Effectively, the contractor pays as if they were a direct employee — including employer NI at 15% for 2025/26 — but without receiving employment rights such as holiday pay, sick pay, or pension auto-enrolment from the client.
Umbrella Companies as an Inside-IR35 Solution
Many contractors working inside IR35 choose to work through a PAYE umbrella company rather than maintaining their own limited company. The umbrella employs the contractor directly, processes all tax deductions, and passes the net pay through. The umbrella company charges a weekly or monthly fee (typically £15–£30/week) for this service. This removes the administrative burden of running a limited company but provides no tax advantage over direct employment.
Some umbrella companies promise to retain a larger proportion of your contract income through complex arrangements (loan schemes, annuity models, offshore trusts). HMRC considers most of these Disguised Remuneration schemes and actively pursues contractors who use them. Stick to compliant PAYE umbrella companies and verify they are on HMRC's Approved Payroll Agent list.
Frequently Asked Questions
No. IR35 applies specifically to workers providing services through an intermediary — almost always a Personal Service Company (limited company). Sole traders who contract directly with clients are subject to ordinary employment status rules under Schedule E / Chapter 2 ITEPA 2003, and HMRC may reclassify them as employees directly without needing IR35. If you operate as a sole trader and HMRC believes you are actually an employee, they can pursue unpaid PAYE and NICs directly from you.
The 5% expenses allowance was a deduction available to contractors inside IR35 under the old Chapter 8 rules — it allowed the contractor's PSC to deduct 5% of turnover to cover the administrative costs of running the company before calculating the deemed payment. This allowance was abolished from April 2021 for all engagements where Chapter 10 applies (i.e., all medium/large clients and all public sector contracts). It may still apply in limited circumstances where a small private sector client leaves the IR35 determination to the PSC.
A single contract with a single client is either inside or outside IR35 as a whole — there is no provision for splitting one engagement. However, a contractor can hold multiple concurrent engagements, each with its own IR35 status. It is perfectly possible to have one contract assessed as outside IR35 and another as inside IR35 at the same time. Each engagement must be assessed independently based on its own facts, contract terms, and working practices.
The consequences depend on when the engagement took place. For pre-April 2021 engagements (or post-April 2021 where a small private sector client applied the old rules), HMRC can raise a tax assessment on the contractor's PSC for unpaid PAYE and NICs, plus interest and potentially penalties if HMRC believes the error was careless or deliberate. For post-April 2021 engagements with medium/large clients, the fee-payer (agency or client) is primarily liable — the contractor's PSC should not bear the tax risk if the client issued an incorrect SDS in good faith.
HMRC states it will stand behind CEST results provided the information entered is accurate and the tool is used in good faith. However, CEST does not adequately test mutuality of obligation in all scenarios, and it returns an "undetermined" result in a significant proportion of cases. Many IR35 specialists, including the Chartered Institute of Taxation, recommend using CEST alongside a detailed contract review and working practices assessment by a qualified IR35 adviser. A positive CEST result (outside IR35) provides some protection but is not a guarantee against HMRC challenge.
IR35 status determinations are a tax matter, not an employment status matter. You cannot challenge an SDS at an Employment Tribunal. The correct route is: (1) use the Client-Led Disagreement Process to formally dispute with the client; (2) if unresolved, seek a formal HMRC ruling; (3) if HMRC assesses tax, appeal through the tax tribunal system (First-Tier Tribunal, Tax Chamber). Note that establishing employment rights (holiday pay, unfair dismissal, etc.) requires a separate Employment Tribunal claim based on employment status — this is entirely separate from the IR35 tax question.