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.
If you're a UK trader seeking to generate returns from accurate outcome forecasting, you'll encounter two primary vehicles: spread betting (through FCA-licensed financial spread betting operators) and prediction markets (through platforms such as Polymarket, Betfair Exchange, or Smarkets). Grasping these distinctions proves essential for effective tax management and tactical decision-making.
What Is Spread Betting in the UK?
The UK's financial spread betting sector is serviced by FCA-regulated providers including IG, CMC Markets, and Spreadex. Participants stake a sum per point shift in a financial asset (FTSE 100, forex, individual equities). Defining features include:
- Leverage: Usually ranges from 2:1 to 20:1 based on asset category
- Tax-free profits: Spread betting enjoys classification as gambling under UK law — returns are tax-exempt, and losses cannot be claimed as deductions
- FCA regulated: Comprehensive safeguards for consumers, mandatory negative balance protection
- Markets: Financial products (indices, forex, commodities, equities) — excludes political or sporting outcomes
- Bid-ask spread: Embedded expense (normally 1–3 pips on major currency pairs)
What Are Prediction Markets?
Prediction markets enable traders to acquire YES/NO binary contracts tied to tangible real-world events. Leading platforms accessible from the UK comprise:
- 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
Every pound earned through spread betting is exempt from both Capital Gains Tax and Income Tax in the UK, provided the account is held with an FCA-authorised spread betting provider. This represents one of the most valuable tax advantages open to UK retail investors. HMRC's official position on financial spread betting confirms this exemption.
Betfair Exchange / Smarkets: Tax-Free
Winnings from UKGC-licensed betting exchanges enjoy the same tax-free treatment — categorised as gambling income under the Gambling Act 2005. Consequently, Betfair and Smarkets deliver an ideal combination: prediction market mechanics alongside unambiguous tax-free standing.
Polymarket: Tax Uncertain
Polymarket returns sit outside both the gambling exemption (lacks UKGC authorisation) and the spread betting exemption (not an FCA-authorised financial spread betting service). 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 instruments (FTSE 100, forex)
- Tax-free status represents a critical requirement with no room for ambiguity
- Your trading focuses on financial price dynamics rather than discrete event outcomes
- You value FCA negative balance safeguards
Choose Prediction Markets When:
- You possess demonstrable skill in predicting particular real-world occurrences (referendums, athletics, scientific breakthroughs)
- You favour a bounded-loss, binary framework (maximum loss equals your stake)
- You need exposure to markets unavailable through spread betting (geopolitics, blockchain developments, meteorological events)
- Reduced commissions relative to conventional sportsbooks matter 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 returns are paramount
- Deploy Smarkets or Betfair Exchange for UK political and sporting events — UKGC-regulated, tax-free, GBP-denominated
- Deploy Polymarket via PolyGram for niche markets absent elsewhere (8,000+ worldwide event contracts) — while acknowledging the tax ambiguity or maintaining thorough records
FAQ — Spread Betting vs Prediction Markets UK
- Is Betfair Exchange classed as spread betting?
- No — Betfair Exchange functions as a betting exchange (UKGC-regulated), distinct from a financial spread betting platform (FCA-regulated). Both deliver tax-free returns under separate UK regulatory schemes. Betfair falls under gambling law; 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 remain tax-free. However, their selection pales beside 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 follows the same binary structure. For leveraged event exposure, financial spread betting represents the sole FCA-regulated option — though it covers only financial instrument prices, excluding specific event outcomes.