In this guide
Key difference: Spread betting winnings enjoy tax-free status under UK legislation. Prediction market returns from decentralised platforms such as Polymarket may trigger Capital Gains Tax or Income Tax liability. For UKGC-authorised, tax-exempt event wagering, Betfair Exchange provides closer parity. For breadth of available markets and competitive fee structures, 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 (via Polymarket, Betfair Exchange, or Smarkets). Grasping these distinctions proves essential for structuring your tax obligations and optimising your trading approach.
What Is Spread Betting in the UK?
Financial spread betting in the UK is delivered by FCA-authorised providers including IG, CMC Markets, and Spreadex. You stake a fixed amount per point shift in a financial asset (FTSE 100, currency pairs, individual equities). Core attributes include:
- Leverage: Commonly ranges from 2:1 to 20:1 contingent on the underlying asset category
- Tax-free profits: The UK legal framework treats spread betting as gambling — returns remain untaxed, and losses cannot be offset against other income
- FCA regulated: Comprehensive investor safeguards, mandatory negative balance protection
- Markets: Restricted to financial instruments (equity indices, currency markets, raw materials, listed equities) — excludes political or sporting outcomes
- Bid-ask spread: Embedded transaction cost (ordinarily 1–3 pips on major currency pairs)
What Are Prediction Markets?
Prediction markets enable you to acquire YES/NO binary contracts tied to tangible real-world events. Primary UK-accessible platforms comprise:
- Polymarket (via PolyGram): 8,400+ markets, USDC-denominated, ~1% effective cost, regulatory status remains ambiguous
- Betfair Exchange: 500 markets, sterling-based, 5% commission rate, UKGC authorised
- Smarkets: 200 markets, sterling-based, 2% commission rate, UKGC authorised
Tax Treatment — The Critical Difference
Spread Betting: Tax-Free
All spread betting returns are exempt from Capital Gains Tax and Income Tax in the United Kingdom, provided your account operates through an FCA-authorised spread betting provider. This represents one of the most advantageous tax positions available to UK retail traders. HMRC's published guidance confirms this treatment for financial spread betting activities.
Betfair Exchange / Smarkets: Tax-Free
UKGC-authorised betting exchange returns similarly remain tax-free — classified as gambling income under the Gambling Act 2005. This positions Betfair and Smarkets as optimal hybrids: prediction market functionality combined with unambiguous tax-free treatment.
Polymarket: Tax Uncertain
Polymarket returns do not neatly align with either the gambling exemption (absent UKGC authorisation) or the spread betting exemption (not FCA-authorised financial spread betting). HMRC could potentially categorise them as CGT or Income Tax liabilities. Consult our regulatory guidance for additional 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 exposure to financial assets (FTSE 100, currency pairs)
- Tax-exempt status is paramount and regulatory certainty is essential
- Your focus is financial price movements rather than discrete event outcomes
- You require FCA-mandated negative balance safeguards
Choose Prediction Markets When:
- You possess demonstrable skill in predicting particular real-world occurrences (political contests, athletic events, scientific developments)
- You favour a capped-loss, binary framework (maximum loss equals your stake)
- You need exposure to markets unavailable through spread betting (political events, blockchain-related outcomes, meteorological forecasts)
- Cost efficiency relative to conventional bookmakers constitutes a significant advantage
Best Combined Approach for UK Traders:
- Establish an FCA-regulated spread betting account (IG, CMC) for financial instrument exposure where leverage and tax exemption are strategically important
- Deploy Smarkets or Betfair Exchange for domestic political and sporting events — UKGC-authorised, tax-exempt, sterling-denominated
- Access Polymarket via PolyGram for markets with no domestic equivalent (8,000+ international event contracts) — whilst acknowledging the tax ambiguity 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-authorised). Both deliver tax-free returns under separate UK regulatory frameworks. 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 providers do — IG Index and Spreadex make available election outcome spread contracts (for instance "Conservative seats at 200–210"). These returns remain tax-exempt. Nevertheless, market depth remains substantially constrained relative to Polymarket's 249 UK-relevant political contracts.
- Is there a UK prediction market with leverage?
- Not conventionally. Betfair and Smarkets operate as binary instruments (stake-only). Polymarket functions as binary. For leveraged event exposure, financial spread betting represents the sole FCA-regulated mechanism — though it exclusively covers financial instrument pricing, excluding discrete event outcomes.