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 trading in the UK, you'll encounter two primary avenues for profiting from accurate outcome forecasts: spread betting (through FCA-licensed financial spread betting operators) and prediction markets (through platforms such as Polymarket, Betfair Exchange, or Smarkets). Grasping these distinctions is essential for effective tax strategy and decision-making.
What Is Spread Betting in the UK?
The UK's financial spread betting sector is served by FCA-regulated operators including IG, CMC Markets, and Spreadex. You stake a sum per point shift in a financial asset (FTSE 100, forex, individual equities). Essential features include:
- Leverage: Ranges from 2:1 to 20:1 based on the underlying asset
- Tax-free profits: Spread betting is legally treated as gambling in the UK — returns are tax-exempt, but losses cannot be claimed
- FCA regulated: Comprehensive investor safeguards, mandatory negative balance protection
- Markets: Financial assets only (indices, forex, commodities, equities) — excludes political or sports outcomes
- Bid-ask spread: Embedded cost (normally 1–3 pips for major currency pairs)
What Are Prediction Markets?
Prediction markets enable you to acquire YES/NO binary contracts linked to real-world events. Primary platforms accessible to UK participants:
- 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, as long as you maintain an FCA-authorised spread betting account. This represents one of the most attractive tax benefits available to UK retail traders. HMRC's official guidance confirms this status for financial spread betting.
Betfair Exchange / Smarkets: Tax-Free
Winnings from UKGC-licensed betting exchanges are also tax-free — classified as gambling income under the Gambling Act 2005. Consequently, Betfair and Smarkets deliver the ideal combination: prediction market functionality PLUS unambiguous tax-free treatment.
Polymarket: Tax Uncertain
Polymarket returns don't clearly fall within either the gambling exemption (lacks UKGC licensing) or the spread betting exemption (not an FCA-authorised financial spread betting provider). HMRC could classify them as CGT or Income Tax liabilities. Consult our prediction market coverage for additional context.
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 is paramount and regulatory clarity is essential
- Your focus is on financial price movements rather than discrete events
- You require FCA negative balance safeguards
Choose Prediction Markets When:
- You possess expertise in predicting particular real-world events (referendums, athletics, research outcomes)
- You prefer a capped-loss, binary framework (maximum loss equals your stake)
- You need access to markets unavailable through spread betting (geopolitics, digital assets, meteorological events)
- Competitive pricing relative to conventional bookies is a key factor
Best Combined Approach for UK Traders:
- Employ an FCA-regulated spread betting account (IG, CMC) for financial instrument exposure where leverage and tax-free treatment are significant
- Employ Smarkets or Betfair Exchange for UK politics and sports — UKGC-regulated, tax-free, GBP-denominated
- Employ Polymarket via PolyGram for markets with no alternative (8,000+ international event contracts) — 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 is a betting exchange (UKGC-regulated), not a financial spread betting service (FCA-regulated). Both deliver tax-free returns within distinct UK legal structures. Betfair falls under gambling classification; spread betting falls under financial speculation — both tax-free, different regulatory bodies.
- Can spread betting firms offer political prediction markets?
- Certain operators do — IG Index and Spreadex provide election outcome spread bets (e.g. "Conservative seats at 200–210"). These returns are tax-free. Nevertheless, selection remains significantly narrower than Polymarket's 249 UK-related political contracts.
- 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 option — though it exclusively covers financial instrument prices, not specific event outcomes.