IR35 Status Determination · SDS Generation · FCSA Payroll Routing

Know your IR35 status in minutes. Generate an SDS in seconds.

AI-powered CEST 8-factor analysis. Chapter 8 & Chapter 10 compliant. Human QA on every borderline case. From £19/month.

Start my IR35 assessment — £19 Hirers: generate an SDS →
Chapter 8 & Chapter 10 ITEPA 2003 compliant
HMRC CEST 8-factor methodology
SDS delivered in under 60 seconds
Human QA on every borderline case
FCSA-accredited payroll routing
Contractors Know your status before you sign the contract
Hirers / PSCs Issue a compliant SDS and track acknowledgements
Agencies Bulk-assess your contractor pool + SafeRec integration
740k+
UK contractors subject to IR35 rules
£1.8bn
HMRC collected in IR35 tax since 2020
31 days
Chapter 10 SDS acknowledgement deadline
8
CEST factors weighted & scored by AI
How it works
From questionnaire to determination in under 10 minutes

Answer 25 plain-English questions about your engagement. AI scores all 8 CEST factors. Human QA reviews borderline cases before the determination is issued.

1

Describe the engagement

Plain-English questions about control, substitution, mutuality, equipment and more. Takes under 10 minutes.

2

AI scores all 8 factors

Claude analyses your responses against all eight CEST factors with weighted scoring. Confidence level calculated.

3

Human QA on borderlines

Every case where AI confidence is below 65% or the outcome is borderline goes to human QA review before release.

4

SDS generated instantly

A Chapter 10-compliant Status Determination Statement, ready to send. Hirers can share a one-click acknowledgement link.

5

Inside IR35? We route you

FCSA-accredited umbrella or payroll provider matched within your sector. Contractor keeps full compliance records.

The three outcomes
What each determination means for you

ir35.law gives you a clear outcome — not a hedge. Human QA ensures borderline cases get a human second opinion.

Outside IR35

Operating through your PSC

Weighted score below 35, AI determination "outside", confidence ≥ 65%. You remain a legitimate self-employed contractor operating outside the off-payroll rules.

Outcome: SDS issued confirming outside status. You continue invoicing through your limited company.
Borderline — Human QA

Human review required

Score between 35–65, or AI confidence below 65%. Every borderline case is reviewed by our human QA team before determination is released.

Outcome: our QA team reviews within 2 working hours. You receive determination with detailed rationale and suggested contract adjustments.
Inside IR35

Off-payroll rules apply

Weighted score above 65, AI determination "inside", confidence ≥ 65%. PAYE and NI must be deducted. An umbrella arrangement is the compliant route.

Outcome: FCSA-accredited umbrella recommended. ir35.law earns a referral fee — your monthly subscription continues at no extra cost.
The 8 CEST factors
Every factor scored. Every weight explained.

ir35.law uses all eight HMRC CEST factors with calibrated weights based on HMRC guidance and tribunal outcomes. No shortcuts. No simplifications.

22%
Control
Who dictates how, when and where the work is done?
20%
Substitution
Can you send someone else to do the work?
18%
Mutuality of Obligation
Is the hirer obliged to offer work, and you to accept it?
14%
Financial Risk
Do you bear financial risk if things go wrong?
8%
Equipment
Do you use your own tools and equipment?
8%
Integration
How embedded are you in the hirer's business?
6%
Exclusivity
Are you free to work for multiple clients at once?
4%
Part and Parcel
Are you treated as part of the permanent workforce?
Chapter 10 — Status Determination Statement
Issue an SDS. Track acknowledgements. Stay protected.

Under Chapter 10 ITEPA 2003, medium and large clients must issue a written SDS. If the contractor or agency doesn't acknowledge within 31 days, PAYE liability passes to the hirer. ir35.law automates the chase.

D0
Day 0 — SDS Issued

Compliant SDS generated and sent

ir35.law generates a Chapter 10-compliant Status Determination Statement with your reasoned determination. Delivered by email with a one-click acknowledgement link.

D7
Day 7 — First chase

Automated acknowledgement reminder

If the contractor or agency hasn't acknowledged, ir35.law sends an automated chase with the original SDS attached.

D14
Day 14 — Second chase

Human QA flagged — formal notice

Our QA team sends a formal notice reminding the contractor of the 31-day statutory acknowledgement requirement (s61P ITEPA 2003).

D21
Day 21 — Legal warning

PAYE liability warning issued

Our QA team sends a pre-action legal warning letter explaining that failure to acknowledge within 31 days will result in PAYE liability transferring to the hirer.

✓
Acknowledged — protected

Contractor has acknowledged the SDS

Token-based acknowledgement recorded. Timestamp and IP logged. Your PAYE liability exposure is eliminated. Audit trail available.

!
Day 31 — Liability transfers if not acknowledged

Escalated to director review

If 31 days have passed without acknowledgement, the hirer bears PAYE liability. ir35.law escalates to your director dashboard and recommends legal action.

Pricing
One tool. Three audiences. One price per determination.

Start with a single assessment for £19. Upgrade to monthly for unlimited determinations, SDS generation and acknowledgement tracking.

Contractor
Contractor Essentials
£19 / month
Or £19 one-off per determination
  • Unlimited IR35 assessments
  • CEST 8-factor scoring report
  • Human QA on borderline cases
  • PDF determination certificate
  • Contract review add-on (£9/contract)
  • FCSA umbrella routing if inside
Start assessment
Recruitment Agency
Agency Bureau
£199 / month
Unlimited contractors · SafeRec integration
  • Bulk contractor assessment
  • SafeRec API integration
  • White-label assessment portal
  • Agency-branded SDS documents
  • Mass SDS issuance and tracking
  • API access for ATS integration
  • Dedicated Human QA SLA (4hr response)
  • Monthly compliance digest
Book agency demo
How we compare
vs. HMRC CEST, IR35 Shield, Qdos

ir35.law is the only platform with AI + human QA review on every borderline case, automated SDS acknowledgement tracking, and FCSA payroll routing built in.

Feature ir35.law HMRC CEST IR35 Shield Qdos
IR35 status determination ✓ AI + human ✓ Tool only ✓ AI-assisted ✓ Manual
Human QA on borderline cases ✓ Mandatory ✗ ✗ ~ Expensive add-on
Chapter 10 SDS generation ✓ Instant ✗ ✓ ~ Manual
SDS acknowledgement tracking ✓ Automated chase ✗ ~ Manual ✗
FCSA payroll routing (inside IR35) ✓ Automatic ✗ ✗ ✗
Contract review add-on ✓ £9/contract ✗ ~ Expensive ✓ Costly
Agency bulk assessment ✓ SafeRec integration ✗ ✓ ✗
Price (contractor, per month) £19 Free £35+ £99+
Common questions
IR35 explained
What is IR35 and does it apply to me?
IR35 is the UK's off-payroll working legislation (ITEPA 2003). It applies if you provide services through a limited company (PSC) and your engagement resembles employment. If caught by IR35, PAYE tax and NI must be paid. From April 2021, medium and large hirers must assess and issue an SDS — contractors no longer self-assess for those engagements.
What's the difference between Chapter 8 and Chapter 10?
Chapter 8 applies when the hirer is a small company (turnover ≤£10.2m, assets ≤£5.1m, employees ≤50). The contractor self-assesses their own IR35 status. Chapter 10 applies when the hirer is medium or large — the hirer must assess and issue a written SDS. ir35.law handles both regimes correctly.
What happens if my hirer doesn't acknowledge the SDS within 31 days?
Under s61P ITEPA 2003, if the contractor or agency doesn't acknowledge the SDS within 31 days, PAYE liability transfers back to the hirer. ir35.law's automated chase schedule (D7, D14, D21, D31) ensures hirers are protected. We log every acknowledgement with timestamp.
I'm inside IR35. What are my options?
The compliant route is to work through an FCSA-accredited umbrella company. They put you on their payroll, deduct PAYE and NI, and pass the net to you. ir35.law automatically routes you to an FCSA provider matched to your sector — we handle the referral.
How accurate is the AI determination?
ir35.law uses Claude to score all 8 CEST factors. Any case where confidence is below 65% or the outcome is borderline is reviewed by our human QA team before the determination is issued. Our target borderline rate is below 15% — clear decisions for most engagements.
Can I use ir35.law for multiple contracts at once?
Yes. Your subscription covers unlimited assessments. Each assessment generates a separate determination and (for inside cases) a separate SDS. Hirers and agencies can manage multiple contractors from a single dashboard.

Know your status. Issue your SDS.
Stay compliant.

Start your first assessment for £19. Generate a compliant SDS in under 60 seconds. Human QA on every borderline case.

Start IR35 assessment — £19 Hirers: generate SDS →

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