Agentic UK IR35 status determination service for small businesses (5–50 staff) engaging contractors, producing HMRC-defensible Status Determination Statements (SDS) and client-contractor disagreement response letters under the off-payroll working rules. Replaces the employment tax specialist or accountant who charges £400–£1,200 per contractor engagement to assess IR35 status, draft the SDS, and produce the appeal response if a contractor challenges the determination.
Why now
HMRC's Check Employment Status for Tax (CEST) tool has been widely criticised as unreliable, and HMRC confirmed in 2024 that it would not update CEST to reflect recent tribunal case law — leaving businesses exposed and driving demand for defensible third-party SDS documentation. Gov.uk and HMRC communications confirm ongoing compliance focus. https://www.gov.uk/search/news-and-communications?keywords=IR35+off-payroll+working+HMRC
Source signals
https://www.gov.uk/search/news-and-communications?keywords=IR35+off-payroll+working+HMRC
Commercial value
HMRC has significantly increased IR35 compliance activity since the 2021 private sector off-payroll rules extension. Any UK business with 2+ contractors must issue SDS documents or face PAYE liability. Employment tax specialists charge £400–£1,200 per contractor assessment. Target: 60,000+ UK SMEs engaging contractors. ACV: £500–£1,500/yr for businesses with 3–15 contractors. Budget line: IR35 compliance is a named cost in every finance team engaging contractors post-2021.
Go-to-market
Target finance directors and ops managers at 10–50 person UK tech, consulting, and professional services firms via LinkedIn. Hook: 'Your CEST determination won't protect you in a tribunal — here's what will.' Price at £99 per SDS pack or £399/yr for up to 10 contractor assessments. First 10 customers via r/Entrepreneur UK threads and direct LinkedIn outreach to companies advertising contractor roles on Indeed/LinkedIn Jobs.
2-week MVP
Single feature: structured contractor engagement questionnaire (substitution rights, control, mutuality of obligation, financial risk) → LLM applies IR35 case law factors and generates a completed, signed-ready Status Determination Statement with a written reasoning section that satisfies the HMRC 'reasonable care' standard. Cut: no ongoing monitoring, no payroll integration, no contractor-facing portal. Manual step: founder reviews each SDS output for edge cases before delivery. Day-1 outcome: an HR or finance manager pays £99 for a defensible SDS document that replaces a £400–£800 employment tax specialist review.
Agent score
0.60 — Commercial score is the strongest of the batch: IR35 compliance is a named, mandatory cost line for any UK business engaging contractors post-2021, the per-unit fee is well-established at £400–£1,200, and HMRC enforcement activity keeps demand persistent. Speed score is high — the MVP is a questionnaire-to-document workflow using established IR35 case law factors, buildable in ~1 week, with first customers reachable via LinkedIn job postings for contractor roles. Defensibility is at the honest midpoint: the legal framework is public, but a proprietary case-law reasoning engine and a track record of tribunal-tested determinations would compound meaningfully over 12–18 months.
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