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 main pathways to generate returns from accurate outcome forecasting: spread betting (through FCA-licensed financial spread betting operators) and prediction markets (through Polymarket, Betfair Exchange, or Smarkets). Grasping these distinctions matters significantly for your tax position and overall trading approach.
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 per-point wager on price fluctuations in financial assets (FTSE 100, currency pairs, individual equities). Core features include:
- Leverage: Commonly 2:1 to 20:1 contingent on the underlying asset
- Tax-free profits: Spread betting holds gambling classification in the UK — winnings incur no tax, losses cannot offset other income
- FCA regulated: Comprehensive investor safeguards, mandatory negative balance protection
- Markets: Financial instruments (indices, currency markets, raw materials, equities) — excludes political or athletic events
- Bid-ask spread: Inherent cost structure (usually 1–3 pips on major currency pairs)
What Are Prediction Markets?
Prediction markets enable you to acquire YES/NO binary contracts contingent on actual-world occurrences. Primary options available 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
Every pound of spread betting profit enjoys exemption from Capital Gains Tax and Income Tax in the UK, provided your account sits with an FCA-authorised operator. This represents one of the most valuable tax advantages open to UK retail traders. HMRC's official guidance corroborates this treatment.
Betfair Exchange / Smarkets: Tax-Free
Winnings from UKGC-licensed betting exchanges receive tax-free treatment — categorised as gambling revenue under the Gambling Act 2005. Consequently, Betfair and Smarkets merge prediction market functionality with 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 might 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 in financial instruments (FTSE 100, currency markets)
- Tax-free status represents a critical requirement with regulatory certainty
- 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 forecasting particular real-world developments (referendums, athletic competitions, scientific breakthroughs)
- You favour a bounded-loss, binary framework (maximum loss equals your stake)
- You require access to markets unavailable through spread betting (geopolitical events, digital asset milestones, meteorological outcomes)
- Minimising expenses relative to conventional bookmakers drives your decision
Best Combined Approach for UK Traders:
- Deploy an FCA-regulated spread betting account (IG, CMC) for financial instrument positions where leverage and tax-free treatment are paramount
- Employ Smarkets or Betfair Exchange for domestic politics and sports — UKGC-regulated, tax-free, sterling-denominated
- Leverage Polymarket via PolyGram for markets with no domestic equivalent (8,000+ worldwide event contracts) — 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 deliver tax-free returns via separate UK regulatory frameworks. Betfair falls under gambling classification; spread betting qualifies as financial speculation — both tax-free, overseen by different authorities.
- 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 qualify for tax-free treatment. Nevertheless, selection remains 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 (stake only). Polymarket functions as binary. Leveraged event trading requires financial spread betting as the sole FCA-regulated mechanism — though it exclusively covers financial instrument prices, excluding discrete event outcomes.