In this guide
Key difference: Spread betting profits are tax-free under UK law. Prediction market winnings (from crypto-based platforms like Polymarket) may be subject to CGT or Income Tax. For UKGC-regulated, tax-free event betting, Betfair Exchange is the closer comparison. For market breadth and lowest fees, Polymarket via PolyGram wins.
As a UK trader, you face a choice between two distinct approaches to monetising your forecasting ability: spread betting (offered by UKGC-licensed financial spread betting operators) and prediction markets (accessible via Polymarket, Betfair Exchange, or Smarkets). Grasping these distinctions is essential for both tax optimisation and developing your trading approach.
What Is Spread Betting in the UK?
The UK's financial spread betting sector is serviced by FCA-regulated operators including IG, CMC Markets, and Spreadex. You stake a sum per point shift in a financial asset (FTSE 100, currency pairs, individual equities). Essential features include:
- Leverage: Commonly ranges from 2:1 to 20:1 based on the asset category
- Tax-free profits: Spread betting enjoys classification as gambling under UK law — returns are tax-exempt, and losses cannot be offset against other income
- FCA regulated: Comprehensive investor safeguards, mandatory negative balance protection
- Markets: Financial assets (stock indices, currency markets, raw materials, equities) — excludes political or sporting predictions
- Bid-ask spread: Inherent transaction cost (usually 1–3 pips on major currency pairs)
What Are Prediction Markets?
Prediction markets enable you to acquire YES/NO binary contracts tied to actual real-world events. Primary UK-accessible platforms include:
- Polymarket (via PolyGram): 8,400+ markets, crypto (USDC), ~1% effective fee, grey zone legally
- Betfair Exchange: 500 markets, GBP, 5% commission, UKGC licensed
- Smarkets: 200 markets, GBP, 2% commission, UKGC licensed
Tax Treatment — The Critical Difference
Spread Betting: Tax-Free
All spread betting returns are exempt from Capital Gains Tax and Income Tax in the UK, provided you trade through an FCA-authorised spread betting operator. This represents one of the most valuable tax advantages accessible to UK retail investors. HMRC's official guidance on financial spread betting confirms this status.
Betfair Exchange / Smarkets: Tax-Free
Winnings from UKGC-licensed betting exchanges are similarly tax-exempt — classified as gambling revenue under the Gambling Act 2005. This positions Betfair and Smarkets as an optimal hybrid: prediction market functionality combined with unambiguous tax-free treatment.
Polymarket: Tax Uncertain
Polymarket returns do not fit neatly into either the gambling exemption (lacks UKGC authorisation) or the spread betting exemption (not an FCA-authorised financial spread betting operator). HMRC could potentially classify them as CGT or Income Tax liabilities. See our UK tax guide.
Comparison — Spread Betting vs Prediction Markets
| Factor | Spread Betting | Betfair/Smarkets | Polymarket (PolyGram) |
|---|---|---|---|
| UK Tax Status | Tax-free ✅ | Tax-free ✅ | Uncertain ⚠️ |
| Regulation | FCA ✅ | UKGC ✅ | Grey zone |
| Leverage | Up to 20:1 | None | None |
| Markets | Financial only | ~200–500 | 8,400+ |
| Max Profit | Unlimited (leveraged) | 2x (binary) | Up to 100x (low-prob YES) |
| Max Loss | Unlimited (leveraged) | Stake only | Stake only |
| GBP Deposits | Yes ✅ | Yes ✅ | Via crypto |
| Effective Costs | 1–3% spread | 2–5% | ~1% |
When to Use Spread Betting vs Prediction Markets
Choose Spread Betting When:
- You seek leveraged positions in financial assets (FTSE 100, forex)
- Tax-free status is paramount and regulatory certainty is essential
- Your focus is on financial price dynamics rather than discrete event outcomes
- You require FCA negative balance safeguards
Choose Prediction Markets When:
- You possess demonstrable skill in predicting particular real-world occurrences (referendums, athletic contests, technological breakthroughs)
- You prefer a bounded-loss, binary framework (maximum loss equals your stake)
- You require access to markets unavailable through spread betting providers (referendums, blockchain events, meteorological outcomes)
- Competitive pricing relative to conventional betting operators matters significantly
Best Combined Approach for UK Traders:
- Deploy an FCA-regulated spread betting account (IG, CMC) for financial instrument positioning where leverage and tax-free returns are strategically important
- Employ Smarkets or Betfair Exchange for UK sporting and political events — UKGC-authorised, tax-exempt, sterling-denominated
- Access Polymarket via PolyGram for niche markets not available elsewhere (8,000+ international event contracts) — while acknowledging tax ambiguity or maintaining thorough records
FAQ — Spread Betting vs Prediction Markets UK
- Is Betfair Exchange classed as spread betting?
- No — Betfair Exchange operates as a betting exchange (UKGC-regulated), distinct from a financial spread betting platform (FCA-regulated). Both deliver tax-free returns under separate UK regulatory frameworks. Betfair falls under gambling classification; spread betting falls under financial speculation — both tax-exempt, overseen by different authorities.
- Can spread betting firms offer political prediction markets?
- Several do — IG Index and Spreadex provide election-outcome spread bets (e.g. "Conservative seats at 200–210"). These returns are tax-exempt. Nevertheless, the range is substantially narrower than Polymarket's 249 UK-focused political contracts.
- Is there a UK prediction market with leverage?
- Not conventionally. Betfair and Smarkets operate on binary terms (stake only). Polymarket similarly operates binary. For leveraged event exposure, financial spread betting remains the sole FCA-regulated mechanism — though it exclusively covers financial instrument valuations, not specific event outcomes.