How to Instruct a Tax Expert Witness
United Kingdom Matters Only
This guide applies to instructing tax expert witnesses in UK tax disputes only: HMRC assessments and investigations, First-tier Tribunal and Upper Tribunal appeals, and civil proceedings where English, Welsh, Scottish, or Northern Irish tax law and tribunal rules govern expert evidence. We do not cover non-UK tax jurisdictions.
For Tax Litigation Counsel
- Identify the technical tax issue, VAT, transfer pricing, IHT, CGT, ERS, SDLT, corporate avoidance, or professional negligence
- Determine expert type, Does the case need a tax technical expert, a forensic accountant, or both? See tax expert vs forensic accountant
- Check FTT category, Standard and complex track cases typically require expert evidence
- Prepare instructions, Specific technical questions to address; CPR Part 35 format required; include summary of material facts
- Provide documents, HMRC assessment, relevant correspondence, tax returns, financial records, and any HMRC reconstruction report
- Expert assessment, Expert reviews HMRC's position and advises on strength of challenge
- Report and hearing, CPR Part 35 report, response to written questions, supplemental report if needed, hearing attendance
For Forensic Accountants
Instruct a separate tax expert when the case raises technical tax analysis questions beyond forensic accounting expertise. Common scenarios include:
- HMRC reconstruction produces a financial figure, but is the correct tax treatment applied to that figure?
- POCA benefit calculation includes tax elements requiring technical analysis
- Professional negligence claim requires assessment of whether tax advice was correct
- Transfer pricing dispute requires arm's length analysis beyond financial accounting
- VAT MTIC case requires knowledge test analysis, not just transaction tracing
Timeline: 7 Steps
| Step | Action | Typical Timing |
|---|---|---|
| 1 | Case assessment, identify expert need | At instruction / appeal filing |
| 2 | Expert selection and initial enquiry | Week 1–2 |
| 3 | Letter of instruction and document bundle | Week 2–4 |
| 4 | Expert report (standard track) | 8–12 weeks |
| 5 | Written questions and supplemental report | Pre-hearing |
| 6 | Hearing preparation and joint expert discussion | 4–8 weeks before hearing |
| 7 | Tribunal hearing attendance | Typically 2–3 years from appeal |
Red Flags When Selecting an Expert
- No active tax practice, tax law changes constantly
- No FTT testimony history in the relevant tax area
- Cannot explain the disputed tax issue clearly to a non-specialist
- Unfamiliar with current HMRC practice and recent tribunal decisions
- Prior adverse judicial comments on their expert evidence
Instruct a tax expert witness
Tell us about your UK tax dispute and we will match you with a qualified expert witness experienced in HMRC enquiries and tribunal proceedings. We aim to respond within one working day.
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