In this guide
Key difference: Spread betting returns are exempt from taxation under UK law. Prediction market returns (from blockchain-based platforms such as Polymarket) may incur CGT or Income Tax liability. For UKGC-regulated, tax-exempt event wagering, Betfair Exchange offers a closer parallel. For sheer market diversity and minimal costs, Polymarket through PolyGram leads the field.
If you're a UK-based trader, two main pathways exist to capitalise on accurate event predictions: spread betting (through FCA-licensed financial spread betting operators) and prediction markets (via Polymarket, Betfair Exchange, or Smarkets). Grasping these distinctions matters significantly for structuring your tax obligations and refining your trading approach.
What Is Spread Betting in the UK?
In the UK, financial spread betting is delivered by 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). Core attributes include:
- Leverage: Usually 2:1 to 20:1 contingent on the asset category
- Tax-free profits: Spread betting is statutorily treated as gambling in the UK — returns carry no tax burden, and losses cannot reduce taxable income
- FCA regulated: Comprehensive investor safeguards, mandatory negative balance safeguards
- Markets: Financial assets (indices, currency pairs, raw materials, equities) — excludes political or athletic outcomes
- Bid-ask spread: Inherent expense (usually 1–3 pips on major currency pairs)
What Are Prediction Markets?
Prediction markets enable you to acquire YES/NO binary agreements tied to actual real-world events. Primary UK-available platforms:
- Polymarket (via PolyGram): 8,400+ contracts, blockchain-based (USDC), ~1% typical expense, uncertain regulatory standing
- Betfair Exchange: 500 contracts, Sterling, 5% commission, UKGC authorised
- Smarkets: 200 contracts, Sterling, 2% commission, UKGC authorised
Tax Treatment — The Critical Difference
Spread Betting: Tax-Free
All spread betting returns are free 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 available to UK retail investors. HMRC's official guidance affirms this treatment for financial spread betting.
Betfair Exchange / Smarkets: Tax-Free
UKGC-authorised betting exchange returns are similarly tax-exempt — classified as gambling proceeds under the Gambling Act 2005. This positions Betfair and Smarkets as an optimal blend: prediction market functionality PLUS unambiguous tax-free standing.
Polymarket: Tax Uncertain
Polymarket returns do not neatly align with either the gambling exemption (lacking 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 further detail.
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 pairs)
- Tax-exempt status is essential and you demand regulatory certainty
- Your focus is on financial price swings rather than discrete event outcomes
- You value FCA negative balance safeguards
Choose Prediction Markets When:
- You possess genuine forecasting skill in particular real-world scenarios (referendums, athletics, scientific breakthroughs)
- You favour a bounded-loss, binary framework (maximum loss equals your stake)
- You need exposure to markets unavailable via spread betting (governmental decisions, digital asset events, meteorological outcomes)
- Reduced fees relative to conventional betting operators are a major consideration
Best Combined Approach for UK Traders:
- Maintain an FCA-regulated spread betting account (IG, CMC) for financial instrument positions where leverage and tax-free treatment are priorities
- Employ Smarkets or Betfair Exchange for UK electoral and sporting markets — UKGC-authorised, tax-exempt, Sterling-denominated
- Access Polymarket via PolyGram for contracts with no alternative venue (8,000+ international event derivatives) — 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-authorised), distinct from a financial spread betting operator (FCA-authorised). Both deliver tax-exempt returns through separate UK regulatory frameworks. Betfair falls under gambling classification; spread betting falls under financial speculation — both tax-exempt, separate 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 carry tax-exempt status. Nevertheless, breadth remains constrained relative to Polymarket's 249 UK-centred electoral contracts.
- Is there a UK prediction market with leverage?
- Not conventionally. Smarkets and Betfair operate as binary (stake only). Polymarket functions as binary. For leveraged event exposure, financial spread betting represents the sole FCA-authorised mechanism — though it exclusively covers financial instrument valuations, not isolated event outcomes.