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 have two distinct avenues to generate returns from accurately predicting outcomes: spread betting (via UKGC-licensed financial spread betting firms) and prediction markets (via Polymarket, Betfair Exchange, or Smarkets). Grasping these distinctions is essential for your tax position and investment approach.
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 sum per point shift in a financial asset (FTSE 100, forex, individual stocks). Core attributes include:
- Leverage: Typically 2:1 to 20:1 contingent on asset category
- Tax-free profits: Spread betting is legally categorised as gambling in the UK — profits incur no tax, losses cannot be offset
- FCA regulated: Comprehensive consumer safeguards, negative balance protection mandated
- Markets: Financial instruments (indices, forex, commodities, individual stocks) — not political or sports outcomes
- Bid-ask spread: Embedded cost (typically 1–3 pips on major forex pairs)
What Are Prediction Markets?
Prediction markets enable you to acquire YES/NO binary contracts on actual-world occurrences. 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 maintain an FCA-authorised spread betting account. This represents one of the most valuable tax advantages open to UK retail investors. HMRC has substantiated this stance in their published guidance regarding financial spread betting.
Betfair Exchange / Smarkets: Tax-Free
UKGC-licensed betting exchange returns are similarly tax-free — handled as gambling income under the Gambling Act 2005. This positions Betfair and Smarkets as an optimal combination: prediction market functionality PLUS unambiguous tax-free treatment.
Polymarket: Tax Uncertain
Polymarket returns do not fit neatly into either the gambling exemption (absent UKGC licence) or the spread betting exemption (not FCA-authorised financial spread betting). HMRC may categorise 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 exposure to financial instruments (FTSE 100, forex)
- Tax-free status is paramount and you demand regulatory certainty
- You're speculating on financial price fluctuations, not discrete event outcomes
- You value FCA negative balance protection
Choose Prediction Markets When:
- You possess an edge in forecasting particular real-world events (elections, sports, science)
- You favour a capped-loss, binary framework (max loss = stake)
- You require access to markets unavailable in spread betting (politics, crypto events, weather)
- Minimising fees relative to conventional bookmakers is a key objective
Best Combined Approach for UK Traders:
- Utilise an FCA-regulated spread betting account (IG, CMC) for financial instrument exposure where leverage and tax-free status are material
- Employ Smarkets or Betfair Exchange for UK politics and sports — UKGC-regulated, tax-free, GBP denominated
- Access Polymarket via PolyGram for markets not found elsewhere (8,000+ global event contracts) — acknowledging the tax ambiguity or maintaining thorough records
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FAQ — Spread Betting vs Prediction Markets UK
- Is Betfair Exchange classed as spread betting?
- No — Betfair Exchange is a betting exchange (UKGC-regulated), not a financial spread betting platform (FCA-regulated). Both deliver tax-free returns under distinct UK legal structures. Betfair is classified as gambling; spread betting is classified as financial speculation — both tax-free, distinct regulators.
- 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 are tax-free. However, selection is substantially narrower than Polymarket's 249 UK-relevant political markets.
- Is there a UK prediction market with leverage?
- Not conventionally. Betfair and Smarkets are binary (stake only). Polymarket is binary. For leveraged event trading, financial spread betting is the sole FCA-regulated option — yet it covers only financial instrument prices, not discrete event outcomes.