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IR35 assessment

IR35 reviewed before you sign — not after HMRC asks.

Status determination, contract review, and working practice analysis for UK contractors operating through a PSC.

IR35 enquiries can backdate up to 6 years. The wrong determination on a single contract can cost £20,000–£100,000+ in tax and NIC. We review every contract before you sign — and document the assessment so it stands up under enquiry.

Who needs IR35 assessment

Is this for you?

  • Contractors operating through a personal service company (PSC)
  • Contractors about to sign a new contract
  • Contractors whose end-client has issued a Status Determination Statement (SDS)
  • Contractors who have received an HMRC IR35 enquiry letter
  • Directors switching from umbrella to PSC
What we do

What's included.

  • Contract review

    Every contract reviewed for IR35 indicators before signing.

  • Working practices analysis

    Substitution rights, control, mutuality of obligation — assessed against your actual day-to-day work.

  • Status determination

    Inside or outside IR35 — documented in writing with reasoning.

  • Tax-impact modelling

    If inside, we model the financial impact and recommend the structure (PSC, umbrella, employed).

  • End-client SDS challenges

    If the end-client has issued an inside SDS you disagree with, we prepare the dispute.

  • Enquiry defence

    If HMRC opens an IR35 enquiry, we defend the historic position with the documented evidence.

How Compliance Vault™ applies

The system that turns this service into a year-round process.

Evidence Pack captures the contract, the SDS (if any), and the working-practices documentation contemporaneously — not reconstructed years later under HMRC pressure. Deadline Lock tracks IR35-relevant dates (HMRC enquiry windows, contract renewal dates).

Read more about Compliance Vault™
Service standards

Documented in your engagement letter. Reviewed annually.

  • WhatsApp typically under 30 min
  • Email within 1 working day
  • Monthly close by the 7th
  • Phone manned reception, typically within 10 min
How it works

Three steps. No back-and-forth.

  1. Step 01: 20-minute discovery call

    We confirm fit and walk through how this service would work for your business.

  2. Step 02: Engagement and onboarding

    Engagement letter, Direct Debit, and Compliance Vault™ setup — typically within 24 hours.

  3. Step 03: Year-round delivery

    Monthly numbers, tracked deadlines, advisory raised — and an Annual Compliance Review every 12 months.

Fee

Bundled with contractor monthly compliance from £150/month. Standalone reviews from £400.

A specific fee is agreed in writing after your 20-minute discovery call. No hourly billing. No surprise charges. No add-on tiers.

Why RR Accountants

What you get from us that you don't get elsewhere.

  • Reviewed before you sign

    Not after the contract is live or after HMRC enquires. Before the signature.

  • Documented in writing

    Every determination is written down. If HMRC asks, the evidence is contemporaneous.

  • Working practices, not just contract

    HMRC looks at what actually happens day-to-day. So do we.

  • Tax-impact modelling

    If inside, we tell you the real financial impact and recommend the right structure.

Frequently asked

IR35 reviewed before you sign — not after HMRC asks — common questions.

  • What is IR35?

    IR35 (the off-payroll working rules) is UK tax legislation that determines whether a contractor working through a personal service company is genuinely self-employed or is effectively a 'disguised employee'. If 'inside IR35', the contractor pays tax and NIC as if employed.

  • Who decides my IR35 status?

    For public-sector and medium/large private-sector clients, the end-client decides via a Status Determination Statement (SDS). For small private-sector clients, the contractor (you) determines status. Either way, the working practices must support the determination — a paper-only assessment isn't enough.

  • What does 'inside IR35' actually cost me?

    Inside IR35 typically increases your tax burden by 25–35% of net contract value compared to outside IR35. On a £100k contract, that's £25,000–£35,000+ in additional tax and NIC. Backdated retrospective determinations can also trigger 6 years of historic tax plus interest and penalties.

  • Can I challenge an inside SDS from my end-client?

    Yes. End-clients are required to consider challenges under the off-payroll rules. We prepare the dispute with reference to the contract, working practices, and HMRC's CEST tool results. End-clients change SDS determinations in roughly 25–40% of well-prepared challenges.

  • What if HMRC opens an IR35 enquiry on a past contract?

    Get in touch immediately — this is a Signal #1 situation. We respond to HMRC, gather contemporaneous evidence from Compliance Vault™, and defend the status determination. Without good evidence, HMRC can apply 'best judgment' retrospectively, which usually means a larger bill.

Related services

Often handled together.

Book a 20-minute call.

We'll confirm whether we're a fit, and if we are, we'll tell you exactly what ir35 assessment would look like for your business.