In this guide
Key difference: Spread betting returns carry no tax liability under UK law. Prediction market returns from blockchain-based venues like Polymarket may incur CGT or Income Tax obligations. For UKGC-authorised, tax-exempt wagering, Betfair Exchange provides closer alignment. For sheer market variety and minimal charges, Polymarket through PolyGram leads.
If you're a UK-based trader, two primary avenues exist for generating returns through accurate outcome forecasting: spread betting (via FCA-authorised financial spread betting operators) and prediction markets (via Polymarket, Betfair Exchange, or Smarkets). Grasping these distinctions proves essential for structuring your tax position and refining your approach.
What Is Spread Betting in the UK?
The UK's financial spread betting sector comprises FCA-authorised providers including IG, CMC Markets, and Spreadex. You stake a sum per point shift in a financial asset (FTSE 100, currency pairs, individual equities). Principal features include:
- Leverage: Customarily 2:1 through 20:1 contingent on the asset category
- Tax-free profits: Spread betting receives legal classification as gambling in the UK — returns incur no tax, and losses cannot be claimed
- FCA regulated: Comprehensive investor safeguards, mandatory negative balance safeguard
- Markets: Financial assets (indices, currency, raw materials, equities) — excludes political or athletic outcomes
- Bid-ask spread: Inherent expense (ordinarily 1–3 pips on primary currency pairs)
What Are Prediction Markets?
Prediction markets enable you to acquire YES/NO contingent contracts tied to factual occurrences. Prominent UK-available platforms include:
- Polymarket (via PolyGram): 8,400+ available markets, blockchain-based USDC, roughly 1% effective cost, regulatory standing ambiguous
- Betfair Exchange: 500 available markets, sterling-denominated, 5% commission structure, UKGC authorised
- Smarkets: 200 available markets, sterling-denominated, 2% commission structure, UKGC authorised
Tax Treatment — The Critical Difference
Spread Betting: Tax-Free
All spread betting returns remain exempt from Capital Gains Tax and Income Tax in the UK, provided your account sits with an FCA-authorised spread betting operator. This represents one of the most advantageous tax provisions accessible to UK retail market participants. HMRC's published materials affirm this classification for financial spread betting activity.
Betfair Exchange / Smarkets: Tax-Free
Winnings from UKGC-authorised betting exchanges qualify as tax-exempt — categorised as gambling proceeds under the Gambling Act 2005. Consequently, Betfair and Smarkets deliver an optimal combination: prediction market functionality PLUS explicit tax-exempt standing.
Polymarket: Tax Uncertain
Polymarket returns do not fit neatly within either the gambling exemption (lacks UKGC authorisation) or the spread betting exemption (not an FCA-authorised financial spread betting service). HMRC could categorise them as CGT or Income Tax liabilities. Consult our regulatory snapshot 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, currency markets)
- Tax-exempt classification matters fundamentally and you demand regulatory certainty
- Your focus centres on financial price fluctuations rather than discrete occurrences
- You value FCA negative balance safeguards
Choose Prediction Markets When:
- You possess an informational advantage in forecasting particular real-world occurrences (referendums, athletics, scientific breakthroughs)
- You favour a bounded-loss, binary framework (maximum loss equals your stake)
- You require access to markets unavailable via spread betting (governmental outcomes, blockchain developments, meteorological events)
- Minimised fees relative to conventional betting operators represent a priority
Best Combined Approach for UK Traders:
- Establish an FCA-regulated spread betting account (IG, CMC) for financial instrument positioning where leverage and tax-free treatment are significant
- Utilise Smarkets or Betfair Exchange for domestic political and athletic events — UKGC-authorised, tax-exempt, sterling-based
- Access Polymarket via PolyGram for markets with no equivalent elsewhere (8,000+ worldwide outcome contracts) — recognising the tax ambiguity or maintaining thorough records
FAQ — Spread Betting vs Prediction Markets UK
- Is Betfair Exchange classed as spread betting?
- No — Betfair Exchange functions as a betting exchange (UKGC-authorised), distinct from financial spread betting platforms (FCA-authorised). Each delivers tax-exempt returns under separate UK regulatory structures. Betfair falls under gambling classification; spread betting falls under financial speculation — both tax-exempt, overseen by distinct regulators.
- Can spread betting firms offer political prediction markets?
- Certain providers do — IG Index and Spreadex furnish election outcome spread bets (e.g. "Conservative seats at 200–210"). These qualify as tax-exempt. Nevertheless, breadth remains substantially constrained relative to Polymarket's 249 UK-focused political offerings.
- Is there a UK prediction market with leverage?
- Not conventionally. Betfair and Smarkets operate as binary (stake only). Polymarket operates as binary. For leveraged event exposure, financial spread betting represents the sole FCA-authorised mechanism — though it covers financial instrument pricing exclusively, excluding discrete outcome scenarios.