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 two primary pathways to monetise accurate forecasting: spread betting (through FCA-licensed financial spread betting operators) and prediction markets (through Polymarket, Betfair Exchange, or Smarkets). Grasping these distinctions proves essential for structuring your tax position and refining your trading approach.
What Is Spread Betting in the UK?
In the UK, financial spread betting is delivered by FCA-authorised providers such as IG, CMC Markets, and Spreadex. You stake a sum per point shift in a financial asset (FTSE 100, currency pairs, individual equities). Core features include:
- Leverage: Commonly ranges from 2:1 to 20:1 across different asset categories
- Tax-free profits: Spread betting is legally treated as gambling in the UK — profits incur no tax, and losses cannot be offset against income
- FCA regulated: Comprehensive investor safeguards, mandatory negative balance protection
- Markets: Financial instruments only (indices, currency markets, commodities, equities) — excludes political or sporting outcomes
- 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 linked 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 free from Capital Gains Tax and Income Tax in the UK, provided you operate through an FCA-authorised spread betting account. This represents one of the most attractive tax benefits available to UK retail traders. HMRC's official guidance on financial spread betting supports this classification.
Betfair Exchange / Smarkets: Tax-Free
Winnings from UKGC-licensed betting exchanges also enjoy tax-free treatment — classified as gambling income under the Gambling Act 2005. This positions Betfair and Smarkets as the optimal combination: prediction market mechanics paired with unambiguous tax-free status.
Polymarket: Tax Uncertain
Polymarket returns fall outside both the gambling exemption (lacking UKGC authorisation) and the spread betting exemption (not an FCA-authorised financial spread betting operator). HMRC could 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 exposure to financial assets (FTSE 100, currency pairs)
- Tax-free treatment is paramount and regulatory clarity is essential
- Your focus is trading financial price movements rather than discrete event outcomes
- You value FCA negative balance protection
Choose Prediction Markets When:
- You possess demonstrable skill in forecasting particular real-world occurrences (political contests, sporting events, scientific breakthroughs)
- You prefer a bounded-loss, binary framework (maximum loss equals your stake)
- You need exposure to outcomes unavailable through spread betting (political events, blockchain developments, meteorological outcomes)
- You prioritise cost efficiency relative to conventional wagering operators
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 priorities
- Deploy Smarkets or Betfair Exchange for UK-focused political and sporting outcomes — UKGC-regulated, tax-free, GBP-denominated
- Deploy Polymarket via PolyGram for niche markets with limited availability elsewhere (8,000+ international event contracts) — accepting 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 financial spread betting platforms (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-free, overseen by different authorities.
- Can spread betting firms offer political prediction markets?
- Certain providers do — IG Index and Spreadex present election outcome spread bets (e.g. "Conservative seats at 200–210"). These returns are tax-free. Nevertheless, the selection remains substantially narrower than Polymarket's 249 UK-relevant political offerings.
- Is there a UK prediction market with leverage?
- Not conventionally. Betfair and Smarkets operate on binary terms (stake only). Polymarket operates on binary terms. For leveraged event trading, financial spread betting represents the sole FCA-regulated pathway — though it exclusively covers financial instrument pricing, not individual event outcomes.