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 principal avenues to capitalise on accurate forecasts of outcomes: spread betting (via UKGC-licensed financial spread betting operators) and prediction markets (via Polymarket, Betfair Exchange, or Smarkets). Grasping these distinctions is essential for effective tax management and tactical planning.
What Is Spread Betting in the UK?
In the UK, financial spread betting 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 equities). Principal features include:
- Leverage: Commonly ranges from 2:1 to 20:1 based on the underlying asset
- Tax-free profits: Spread betting carries legal classification as gambling in the UK — winnings incur no tax, and losses cannot be offset
- FCA regulated: Comprehensive investor safeguards, mandatory negative balance protection
- Markets: Financial instruments only (indices, forex, commodities, equities) — excludes political or sports predictions
- Bid-ask spread: Inherent cost structure (normally 1–3 pips on major forex pairs)
What Are Prediction Markets?
Prediction markets enable you to acquire YES/NO binary contracts tied to genuine real-world occurrences. Leading UK-accessible platforms 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 spread betting gain is exempt 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 substantial tax advantages open to UK retail traders. HMRC has substantiated this stance through their published guidance on financial spread betting.
Betfair Exchange / Smarkets: Tax-Free
Winnings from UKGC-licensed betting exchange activity are equally tax-free — categorised as gambling income under the Gambling Act 2005. This positions Betfair and Smarkets as an optimal hybrid: prediction market functionality combined with transparent tax-free treatment.
Polymarket: Tax Uncertain
Polymarket gains do not neatly fit either the gambling exemption (absent UKGC licence) or the spread betting exemption (lacking FCA-authorised financial spread betting status). HMRC could classify them as CGT or Income Tax liabilities. Consult 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 on financial instruments (FTSE 100, forex)
- Tax-free treatment is paramount and regulatory clarity is essential
- Your focus is 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 events (political contests, athletics, scientific developments)
- You favour a capped-loss, binary framework (maximum loss equals your stake)
- You require access to markets unavailable through spread betting (geopolitics, digital assets, climate)
- Minimised costs relative to conventional betting operators matter significantly
Best Combined Approach for UK Traders:
- Deploy an FCA-regulated spread betting account (IG, CMC) for financial instrument positions where leverage and tax-free status are important
- Deploy Smarkets or Betfair Exchange for domestic political and athletic markets — UKGC-regulated, tax-free, GBP denominated
- Deploy Polymarket via PolyGram for markets with no alternative source (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 gains under separate UK legal structures. Betfair falls under gambling classification; spread betting falls under financial speculation — both tax-free, separate regulators.
- Can spread betting firms offer political prediction markets?
- Certain operators do — IG Index and Spreadex furnish election outcome spread bets (e.g. "Conservative seats at 200–210"). These remain tax-free. Nevertheless, product selection pales beside Polymarket's 249 UK-focused political markets.
- Is there a UK prediction market with leverage?
- Not formally. Betfair and Smarkets operate as binary (stake only). Polymarket is binary. For leveraged event trading, financial spread betting represents the sole FCA-regulated option — yet it covers only financial instrument pricing, not discrete event outcomes.