In this guide
Key difference: Spread betting returns are exempt from tax under UK law. Prediction market returns (from decentralised platforms such as Polymarket) may face CGT or Income Tax liability. For UKGC-authorised, tax-exempt event wagering, Betfair Exchange offers closer parity. For sheer market depth and minimal fees, Polymarket accessed through PolyGram leads the field.
As a British trader, you possess two principal pathways to generate returns from accurate outcome forecasting: spread betting (via FCA-licensed 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?
Financial spread betting in the UK is delivered by FCA-authorised providers such as IG, CMC Markets, and Spreadex. You stake a sum per point shift in a financial asset (FTSE 100, currency pairs, individual equities). Central features include:
- Leverage: Commonly 2:1 through 20:1 contingent on the asset category
- Tax-exempt returns: Spread betting receives legal classification as gambling in the UK — winnings incur no tax, losses cannot be offset
- FCA authorised: Comprehensive investor safeguards, mandatory negative balance cover
- Markets: Financial assets (indices, currency pairs, raw materials, equities) — excludes political or sporting forecasts
- Bid-ask spread: Embedded cost (normally 1–3 pips on primary currency pairs)
What Are Prediction Markets?
Prediction markets enable you to acquire YES/NO contracts pegged to actual real-world occurrences. Leading UK-available selections include:
- Polymarket (via PolyGram): Over 8,400 markets, blockchain-settled (USDC), roughly 1% net cost, regulatory standing uncertain
- Betfair Exchange: Approximately 500 markets, sterling-denominated, 5% commission, UKGC authorised
- Smarkets: Around 200 markets, sterling-denominated, 2% commission, UKGC authorised
Tax Treatment — The Critical Difference
Spread Betting: Tax-Free
Every spread betting return is free from Capital Gains Tax and Income Tax in the UK, provided your account sits with an FCA-authorised spread betting operator. This represents among the most valuable tax advantages accessible to UK private traders. HMRC has formally endorsed this treatment in published materials on financial spread betting.
Betfair Exchange / Smarkets: Tax-Free
UKGC-authorised exchange wagering returns remain tax-exempt — categorised as gambling income under the Gambling Act 2005. This positions Betfair and Smarkets as an optimal combination: prediction market functionality PLUS explicit tax-exempt standing.
Polymarket: Tax Uncertain
Polymarket returns sit outside both the gambling exemption (lacking UKGC authorisation) and the spread betting exemption (not an FCA-authorised financial spread betting service). HMRC could classify them as CGT or Income Tax obligations. Consult our comprehensive tax resource.
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 participation in financial assets (FTSE 100, currency pairs)
- Tax-exempt treatment is paramount and regulatory certainty is essential
- Your focus centres on financial price dynamics rather than discrete event outcomes
- You require FCA-mandated negative balance safeguards
Choose Prediction Markets When:
- You possess demonstrable skill in forecasting particular real-world developments (referendums, athletics, scientific breakthroughs)
- You favour a bounded-loss, binary framework (maximum loss equals your stake)
- You require access to markets unavailable through spread betting platforms (geopolitics, blockchain events, meteorological outcomes)
- Competitive pricing relative to conventional betting operators matters significantly
Best Combined Approach for UK Traders:
- Establish an FCA-regulated spread betting position (IG, CMC) for financial instrument exposure where leverage and tax-exempt returns are priorities
- Deploy Smarkets or Betfair Exchange for domestic politics and athletics — UKGC-authorised, tax-exempt, sterling-based
- Leverage Polymarket through PolyGram for markets with no domestic equivalent (8,000+ worldwide event 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 operates as a betting exchange (UKGC-authorised), distinct from financial spread betting (FCA-regulated). Both deliver tax-exempt returns via separate UK legal structures. Betfair falls under gambling classification; spread betting falls under financial speculation — both tax-exempt, overseen by different authorities.
- Can spread betting firms offer political prediction markets?
- Certain operators do — IG Index and Spreadex furnish election outcome spread wagers (e.g. "Conservative seats at 200–210"). These carry tax-exempt status. Nevertheless, product breadth remains substantially constrained relative to Polymarket's 249 UK-focused political contracts.
- Is there a UK prediction market with leverage?
- Not conventionally. Betfair and Smarkets operate on binary principles (stake only). Polymarket functions identically. For leveraged event exposure, financial spread betting represents the sole FCA-regulated mechanism — though it exclusively covers financial instrument valuations, excluding discrete event outcomes.