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 powerful mechanisms for capitalising on accurate forecasts: spread betting (through FCA-licensed financial spread betting operators) and prediction markets (through Polymarket, Betfair Exchange, or Smarkets). Grasping these distinctions is essential for optimising your tax position and selecting the right trading vehicle.
What Is Spread Betting in the UK?
Financial spread betting in the UK is delivered by FCA-regulated operators such as IG, CMC Markets, and Spreadex. You stake a per-point amount on price movements in a financial asset (FTSE 100, forex, individual equities). Core features include:
- Leverage: Typically 2:1 to 20:1 based on the underlying asset category
- Tax-free profits: Spread betting is legally treated as gambling in the UK — winnings incur no tax, losses cannot be claimed as deductions
- FCA regulated: Comprehensive investor safeguards, mandatory negative balance protection
- Markets: Financial instruments (indices, forex, commodities, equities) — excludes political or sports outcomes
- Bid-ask spread: Embedded cost (usually 1–3 pips on major currency pairs)
What Are Prediction Markets?
Prediction markets enable you to acquire YES/NO binary contracts linked to actual real-world events. Leading 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 gains are exempt from Capital Gains Tax and Income Tax in the UK, provided your account is held with an FCA-authorised spread betting operator. This represents one of the most attractive tax advantages accessible to UK retail traders. HMRC's official guidance confirms this favourable treatment for financial spread betting.
Betfair Exchange / Smarkets: Tax-Free
Winnings on UKGC-licensed betting exchanges are likewise tax-free — classified as gambling income under the Gambling Act 2005. This positions Betfair and Smarkets as an ideal hybrid: prediction market functionality combined with unambiguous tax-free treatment.
Polymarket: Tax Uncertain
Polymarket winnings sit in a legal grey area — they don't qualify for the gambling exemption (lacking UKGC authorisation) or the spread betting exemption (not an FCA-authorised financial spread betting service). HMRC could classify them as CGT or Income Tax liabilities. Refer to our editorial archive for detailed analysis.
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 on financial instruments (FTSE 100, currency pairs)
- Tax-free status is paramount and regulatory clarity is essential
- Your strategy centres on financial price dynamics rather than discrete event outcomes
- You require FCA negative balance safeguards
Choose Prediction Markets When:
- You possess an edge forecasting particular real-world events (referendums, athletics, scientific breakthroughs)
- You favour a capped-loss, binary structure (maximum loss equals your stake)
- You need exposure to markets unavailable through spread betting (geopolitics, blockchain developments, meteorological events)
- Minimising fees relative to conventional betting operators matters to your strategy
Best Combined Approach for UK Traders:
- Deploy an FCA-regulated spread betting account (IG, CMC) for financial instrument positions where leverage and tax-free treatment are crucial
- Deploy Smarkets or Betfair Exchange for UK-focused events and sports — UKGC-regulated, tax-free, GBP-denominated
- Deploy Polymarket via PolyGram for niche markets unavailable elsewhere (8,000+ global event contracts) — with careful tax documentation or acceptance of the regulatory uncertainty
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 legal structures. Betfair falls under gambling law; spread betting falls under financial services law — both tax-free, different regulatory bodies.
- Can spread betting firms offer political prediction markets?
- Some do — IG Index and Spreadex provide election outcome spread bets (e.g. "Conservative seats at 200–210"). These attract no tax. However, the range is substantially narrower than Polymarket's 249 UK-relevant political contracts.
- Is there a UK prediction market with leverage?
- Not conventionally. Betfair and Smarkets operate on binary terms (stake only). Polymarket is binary. For leveraged event-based trading, financial spread betting remains the sole FCA-regulated option — though it only covers financial instrument prices, not specific event outcomes.