IR35 in 2026: Tools That Help
UK Contractors Stay Compliant

What Is IR35?

IR35 is UK tax legislation designed to prevent "disguised employment" — where someone works like an employee but bills through a limited company to pay less tax. HMRC uses a set of factors to decide whether a contractor is genuinely self-employed or effectively employed.

The key factors HMRC considers:

• Substitution — can you send someone else to do the work?
• Control — does the client control how, when, and where you work?
• Mutuality of obligation — is the client obliged to offer work and are you obliged to accept?
• Financial risk — do you bear financial risk on the engagement?
• Integration — are you integrated into the client's organisation?

Who Decides Your IR35 Status?

Since April 2021, for medium and large private sector clients, the end client is responsible for determining IR35 status — not you. They issue a Status Determination Statement (SDS). For small clients (under 50 employees, under £10.2m turnover, under £5.1m balance sheet), you remain responsible.

For public sector engagements, the public body determines status.

Tools That Help With IR35

No accounting software directly solves IR35 — that requires a status assessment. But these tools help contractors manage their situation:

1. HMRC's CEST Tool (Free)

HMRC's Check Employment Status for Tax (CEST) tool gives a determination based on your answers. It's free, and HMRC stands behind its results if you answer accurately. Use it for each new engagement. Not perfect, but it's the official tool.

HMRC CEST Tool (gov.uk) →

2. Qdos Contractor (IR35 Insurance + Assessments)

Qdos provides professional IR35 contract reviews, status assessments, and IR35 insurance (tax investigation cover). If you're outside IR35 on a medium/large client engagement, having a Qdos review adds a layer of protection. Their IR35 insurance means if HMRC investigates, you're covered.

3. FreeAgent (Accounting — HMRC Recognised)

Whether you're inside or outside IR35, you'll need solid accounting. FreeAgent is the most popular choice for UK contractors — it handles limited company accounts, payroll, VAT, Self Assessment, and MTD. Free with NatWest/RBS business accounts.

Try FreeAgent free for 30 days →

4. Xero (Accounting — Best for Accountant Collaboration)

If you work with a contractor accountant (recommended for limited companies), Xero is what most UK contractor accountants use. It makes collaboration easy — your accountant can access your books directly, handle your payroll, and keep you compliant. From £16/mo.

Try Xero free for 30 days →

5. Notion AI / Claude Pro (Contract Documentation)

AI tools like Claude Pro and Notion AI are increasingly used by contractors to draft and review contract language, create working practice documentation, and write outside-IR35 evidence (e.g., substitution clauses, project scope definitions). These don't replace a specialist IR35 review but help you create the right paper trail.

If You're Caught Inside IR35

If your engagement is deemed inside IR35, your income from that contract is treated as employment income. The key practical steps:

• Your fee-payer (agency or client) deducts PAYE and NI before paying you
• You can still pay yourself a salary and dividends from your limited company from other (outside IR35) income
• An umbrella company is often the simplest option for inside-IR35 contracts
• Your accounting software still matters — you need to track the net income correctly

IR35 For Sole Traders

If you operate as a sole trader (not a limited company), IR35 does not apply to you. Instead:

• You pay Income Tax and Class 4 National Insurance on your profits via Self Assessment
• There's no distinction between "inside" and "outside" IR35 for sole traders
• Your focus should be on whether HMRC classifies you as employed vs self-employed — a similar but separate question

Tools like GoSimpleTax (£29.99/year) or FreeAgent handle Self Assessment for sole traders. See our guide to the best tax tools for UK sole traders.

Summary

IR35 compliance for limited company contractors comes down to:

• Getting a proper status assessment for each engagement (CEST or Qdos review)
• Having your contracts reviewed for outside-IR35 language
• Documenting your working practices (especially substitution and control)
• Using solid accounting software to manage your finances correctly — whether inside or outside IR35