In this guide
Key difference: Spread betting returns enjoy tax exemption under UK legislation. Prediction market returns (from decentralised platforms such as Polymarket) could face Capital Gains Tax or Income Tax liability. For UKGC-authorised, tax-exempt event wagering, Betfair Exchange provides the nearest equivalent. For market depth and competitive pricing, Polymarket accessed through PolyGram leads the field.
As a UK-based trader, you have two primary 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 structuring your tax position and selecting your trading approach.
What Is Spread Betting in the UK?
In the UK, financial spread betting is delivered by FCA-regulated operators including IG, CMC Markets, and Spreadex. You stake a per-point amount on directional movements in a financial asset (FTSE 100, currency pairs, individual equities). Principal features include:
- Leverage: Usually 2:1 to 20:1 contingent on the underlying asset
- Tax-free profits: Spread betting holds the legal status of gambling in the UK — returns are not taxable, and losses cannot offset other income
- FCA regulated: Comprehensive investor safeguards, mandatory negative balance safeguard
- Markets: Financial products (indices, currency markets, raw materials, equities) — excludes political or sporting contests
- Bid-ask spread: Embedded expense (normally 1–3 pips on primary currency pairs)
What Are Prediction Markets?
Prediction markets enable you to acquire YES/NO binary agreements on tangible world occurrences. Primary UK-available platforms include:
- Polymarket (via PolyGram): 8,400+ markets, USDC-denominated, roughly 1% total cost, uncertain regulatory standing
- Betfair Exchange: 500 markets, sterling-based, 5% commission structure, UKGC authorised
- Smarkets: 200 markets, sterling-based, 2% commission structure, UKGC authorised
Tax Treatment — The Critical Difference
Spread Betting: Tax-Free
All spread betting returns are excluded from Capital Gains Tax and Income Tax in the UK, provided you maintain an FCA-authorised spread betting account. This represents among the most valuable tax benefits accessible to UK private traders. HMRC has formally documented this position in their published materials on financial spread betting.
Betfair Exchange / Smarkets: Tax-Free
Winnings from UKGC-authorised betting exchange accounts are likewise tax-exempt — categorised as gambling revenue under the Gambling Act 2005. This positions Betfair and Smarkets as offering the optimal combination: prediction market functionality alongside unambiguous tax-free treatment.
Polymarket: Tax Uncertain
Polymarket returns do not neatly align with either the gambling exemption (lacks UKGC authorisation) or the spread betting exemption (not an FCA-authorised financial spread betting service). HMRC might categorise them as Capital Gains Tax or Income Tax obligations. Consult our comprehensive UK 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 positions in financial instruments (FTSE 100, currency markets)
- Tax-exempt status is essential and you require regulatory certainty
- Your focus is on financial price dynamics rather than discrete event outcomes
- You value FCA-mandated negative balance safeguards
Choose Prediction Markets When:
- You possess forecasting skill in particular real-world events (referendums, athletics, academic breakthroughs)
- You favour a bounded-loss, binary framework (maximum loss equals your stake)
- You require exposure to markets unavailable through spread betting (elections, blockchain developments, meteorological outcomes)
- Minimising fees relative to conventional betting operators matters
Best Combined Approach for UK Traders:
- Establish an FCA-regulated spread betting account (IG, CMC) for financial asset exposure where leverage and tax exemption are priorities
- Employ Smarkets or Betfair Exchange for domestic political and sporting events — UKGC-authorised, tax-exempt, sterling-denominated
- Access Polymarket via PolyGram for niche markets absent elsewhere (8,000+ international event agreements) — while managing tax uncertainty or maintaining thorough documentation
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 platforms (FCA-regulated). Both deliver tax-exempt returns under separate UK legal structures. Betfair falls under gambling classification; spread betting falls under financial speculation — both enjoy tax exemption, overseen by different authorities.
- Can spread betting firms offer political prediction markets?
- Certain providers do — IG Index and Spreadex deliver election outcome spread bets (e.g. "Conservative seats at 200–210"). These attract no tax. Nevertheless, the breadth of offerings remains considerably narrower than Polymarket's 249 UK-relevant election markets.
- Is there a UK prediction market with leverage?
- Not conventionally. Smarkets and Betfair operate as binary (stake-only). Polymarket operates as binary. For leveraged event exposure, financial spread betting represents the sole FCA-authorised pathway — though it exclusively covers financial instrument valuations, not specific event outcomes.