What Is Off-Payroll Working? The IT Contractor’s Guide to IR35, SDS & Take-Home Pay

A practical breakdown of IR35 status, financial impact, and compliance for tech contractors operating through a Personal Service Company (PSC) or umbrella arrangement.

Disclaimer: This guide is general information for UK and cross-border tech contractors, not personalised tax or legal advice. IR35 status depends on your specific contract and working practices. Get a qualified accountant or IR35 specialist to review your own position where appropriate.

1. What Is Off-Payroll Working? (And How IR35 Applies)

Understanding what off-payroll working actually means, and how IR35 affects your income, is essential for any contractor operating through a Personal Service Company (PSC). If an engagement is classed as inside IR35, the relevant earnings are generally taxed through PAYE in a similar way to employment income. That tax treatment does not automatically give you the same employment-law rights or benefits as a directly employed member of staff.

Who decides your status depends on the client. Public authorities and medium or large private-sector clients generally make the IR35 determination and, where required, issue a Status Determination Statement (SDS). With small private-sector clients, responsibility generally stays with the worker’s intermediary. Where the client makes the decision, it must take reasonable care.

2. Inside vs. Outside IR35: The Financial & Operational Reality

Factor	Outside IR35 (PSC)	Inside the off-payroll rules
Tax treatment	The PSC remains responsible for its company taxes; money taken personally may include salary and dividends, subject to the relevant rules.	The deemed direct payment is generally subject to PAYE Income Tax and employee National Insurance.
Employer National Insurance	Depends on salary and other payments made by the company; dividends are not earnings for Class 1 National Insurance.	The deemed employer is responsible for employer National Insurance on the relevant payment. In an umbrella arrangement, the assignment rate and employment pay are not necessarily the same figure.
Take-home pay	Depends on company profit, expenses, salary, dividends, pension contributions and the contractor’s wider tax position.	Depends on the agreed rate, PAYE deductions, National Insurance, pension arrangements and, where relevant, umbrella costs.
Business expenses	Qualifying company expenses may reduce taxable company profit, subject to the normal tax rules.	Expense treatment is more restricted and depends on the expense and engagement circumstances.
Working relationship	Contract terms and actual working practices should support a genuinely independent supplier relationship.	The tax rules apply because the hypothetical direct relationship is considered employment for tax purposes.

Financial scenario: £500/day, 220 working days (£110,000 gross revenue)

At £500 a day for 220 days, the headline contract value is £110,000. That figure alone is not enough to produce a reliable outside-versus-inside take-home comparison. The result can change materially depending on:

• Company expenses and allowable deductions
• Salary and dividend choices
• Pension contributions
• Other personal income
• Your country within the UK and applicable tax bands
• The fee-payer arrangement and any umbrella employment costs

Starting point	Outside IR35 through a PSC	Inside the off-payroll rules
Headline contract value	£110,000 before company costs and taxes	£110,000 headline value, but the amount treated as gross employment pay may differ depending on the contractual payment chain
Key deductions	Company expenses, Corporation Tax and personal tax on money extracted from the company	PAYE Income Tax and employee National Insurance on the deemed employment payment; employer National Insurance is the deemed employer’s liability
Typical financial outcome	More flexibility over how company profits are extracted; take-home varies with allowable expenses, salary/dividend choices and pension contributions.	Employment-style deductions are applied upfront; take-home is reduced by PAYE and employee National Insurance, with umbrella costs potentially relevant where an umbrella company is used.

The important point is that an inside determination can change the tax treatment substantially, but there is no universal £8,000–£13,000 annual gap. A meaningful comparison needs to use the actual engagement terms and the contractor’s circumstances.

💡 Action Item: Compare the actual net position before accepting a role. Ask for a clear breakdown of the assignment rate, taxable gross pay and deductions if an umbrella company is involved, and use a qualified accountant or reputable calculator for your own circumstances.

3. Key IR35 Status Factors (How the Overall Relationship Is Assessed)

Status is not decided by a job title or a single contract clause. The contract and the reality of the working relationship need to be considered together. Personal service, control and mutuality of obligation are important factors, but the overall picture can also include matters such as financial risk, provision of equipment, integration into the client’s organisation and whether the worker is genuinely operating a business on their own account.

1. Personal Service & Right of Substitution

If you are contractually and practically required to perform the work personally, that can point toward employment. A genuine and workable right to provide a substitute can point the other way, but the details matter, including any conditions on substitution and whether the right reflects the real arrangement rather than existing only on paper. It should be considered alongside the other status factors rather than treated as an automatic outside-IR35 test.

2. Control

This covers how, when, and where the work gets done. The more the client dictates your working hours, methodology, tools, and day-to-day supervision in the way a line manager might, the more the relationship can resemble employment. Genuine contractors are typically engaged for an outcome, not for their time.

3. Mutuality of Obligation (MOO)

Mutuality of obligation looks at the obligations between the parties, including whether work must be offered and accepted. It is a technical area of employment-status law and should not be reduced to whether a project has a fixed end date. Project scope, termination rights, obligations between assignments and the practical relationship can all be relevant to the wider status assessment.

⚠️ Red Flag: Fixed working hours, close supervision, line-management responsibilities, staff-style appraisals or deep integration into the client’s organisation can be relevant indicators when assessing status. None of these points decides IR35 by itself; the contract and actual working practices need to be assessed as a whole.

4. Navigating the Status Determination Statement (SDS) & Appeals

An SDS records the client’s conclusion about the worker’s employment status for tax and the reasons for that conclusion. Where the client is responsible for the determination, it must take reasonable care in reaching it. A client may adopt policies about how it engages contractors, but an SDS issued under the rules should reflect a status determination made with the required reasonable care.

What to do if you disagree with an Inside IR35 SDS

1. Request the reasoning in writing. Ask specifically what tool or methodology was used (e.g. CEST) and what factors drove the decision.
2. Compare the SDS with the contract and actual working practices. Identify specific facts or assumptions you believe are incorrect and explain why they matter to the overall status assessment.
3. Use the client’s mandatory Status Disagreement Process. Clients must have one under the off-payroll rules and must respond within 45 days.
4. Submit your disagreement in writing with relevant evidence. Address substitution, control and mutuality of obligation where applicable, but also include any other facts that materially affect the overall relationship.
5. Escalate through your agency if the client is unresponsive. The fee-payer also has an interest in getting the determination right.
6. Decide your walk-away point in parallel. If the determination will not change and the day rate does not compensate for it, consider whether the engagement still works for you.

💡 Action Item: Keep records that accurately reflect how the engagement operates — for example, agreed project scope, changes to deliverables, decisions about how work is performed and any genuine discussions about substitution or subcontracting. The aim is not to manufacture an outside-IR35 paper trail; it is to retain evidence of the real working relationship if the status is later questioned.

5. Recommended Compliance Tools & IR35 Defence Stack

Treat IR35 compliance as ongoing operational hygiene, not a one-off contract check. A few categories of tools and services do most of the heavy lifting:

Independent contract and working-practices review → A specialist can review the written terms alongside how the engagement is expected to operate. This can help identify inconsistencies before work starts, although no private review can guarantee how a client, HMRC or a court would ultimately assess status.

IR35 tax-investigation insurance → Some policies can cover professional representation costs and may provide additional tax-related cover, depending on their wording, exclusions and eligibility requirements. Compare the actual policy terms rather than assuming every product provides the same protection. For cross-border E&O, Cyber, and commercial coverage beyond tax inquiries, read our full International IT Consultant Insurance guide →.

Accounting software and professional advice: Software such as FreeAgent or Xero can help a PSC maintain bookkeeping and records, but the software does not determine IR35 status or decide whether an expense is allowable. Tax treatment should be checked against HMRC rules and, where necessary, with a qualified adviser.

6. Four Practices That Can Support a Genuine Contractor Relationship

1. Use commercial terms that reflect the real engagement. Milestones, deliverables and project-based terms can be relevant where they genuinely match the work, but invoicing by time does not by itself make an engagement inside IR35.
2. Maintain a genuine business identity where appropriate. A company website, business insurance or separate email domain may support the wider picture of operating independently, but these are secondary indicators and do not determine IR35 status.
3. Keep working practices consistent with the agreed relationship. Consider whether supervision, staff processes, internal responsibilities and control over how the work is performed match the contract. Avoid artificial arrangements created only to influence status.
4. Do not treat client count as a status test. Having multiple clients may support the broader picture of being in business on your own account, but a contractor can have only one client at a particular time and still be outside IR35. Each engagement must be assessed on its own facts.

This guide reflects general UK tax rules for the 2026/27 tax year and off-payroll working legislation as it currently stands. Rules, rates and HMRC guidance change, so confirm your position with a qualified accountant or IR35 specialist before making contract or structuring decisions.

Official References

• GOV.UK: Understanding off-payroll working (IR35)
• GOV.UK: Check Employment Status for Tax (CEST)