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-based trader, you can generate returns through two primary mechanisms: spread betting (via FCA-licensed financial spread betting operators) and prediction markets (via Polymarket, Betfair Exchange, or Smarkets). Grasping these distinctions is essential for effective tax strategy and risk management.
What Is Spread Betting in the UK?
The UK's FCA-regulated spread betting sector includes operators 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: Ranges from 2:1 to 20:1 based on the underlying asset
- Tax-free profits: Under UK law, spread betting is legally treated as gambling — gains escape taxation, but losses cannot be claimed
- FCA regulated: Comprehensive investor safeguards, mandatory negative balance shield
- Markets: Restricted to financial assets (equity indices, currency markets, raw materials, equities) — excludes political or sporting events
- Bid-ask spread: Embedded cost (typically 1–3 pips for major currency pairs)
What Are Prediction Markets?
Prediction markets enable you to acquire YES/NO binary contracts tied to actual real-world events. Leading UK-accessible platforms comprise:
- Polymarket (via PolyGram): 8,400+ markets, crypto (USDC), ~1% effective fee, regulatory status ambiguous
- 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 concessions accessible to UK private traders. HMRC's published guidance affirms this treatment for financial spread betting activities.
Betfair Exchange / Smarkets: Tax-Free
Winnings from UKGC-licensed betting exchanges receive identical tax-free treatment — classified as gambling income under the Gambling Act 2005. Consequently, Betfair and Smarkets deliver the optimal combination: prediction market functionality PLUS unambiguous tax-free standing.
Polymarket: Tax Uncertain
Polymarket returns lack clear alignment with either the gambling exemption (absent UKGC authorisation) or the spread betting exemption (not an FCA-authorised financial spread betting operator). HMRC could 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 positions in financial markets (FTSE 100, currency pairs)
- Tax-free status is paramount and regulatory certainty is essential
- Your focus is on financial price dynamics, not discrete event outcomes
- You require FCA negative balance safeguards
Choose Prediction Markets When:
- You possess demonstrable skill in forecasting particular real-world occurrences (referendums, athletic contests, scientific breakthroughs)
- You favour a bounded-loss, binary framework (maximum loss = initial stake)
- You require exposure to markets unavailable through spread betting (geopolitics, blockchain developments, meteorological events)
- Minimising costs relative to conventional betting operators is a key objective
Best Combined Approach for UK Traders:
- Maintain an FCA-regulated spread betting account (IG, CMC) for financial market exposure where leverage and tax-free returns are advantageous
- Employ Smarkets or Betfair Exchange for UK elections and sporting events — UKGC-regulated, tax-free, sterling-denominated
- Access Polymarket via PolyGram for niche markets with no alternative venue (8,000+ global event contracts) — whilst acknowledging 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 generate tax-free returns under separate UK regulatory frameworks. Betfair falls under gambling law; spread betting falls under financial regulation — both tax-exempt, distinct supervisors.
- 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 remain tax-free. Market selection, however, is substantially narrower than Polymarket's 249 UK-focused political contracts.
- Is there a UK prediction market with leverage?
- Not conventionally. Betfair and Smarkets operate as binary contracts (stake-only). Polymarket functions identically. For leveraged event exposure, financial spread betting represents the sole FCA-regulated mechanism — though it exclusively covers financial instrument pricing, not specific event outcomes.