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 face CGT or Income Tax liability. For UKGC-regulated, tax-exempt event wagering, Betfair Exchange provides the closest alternative. For sheer market selection and minimal fees, Polymarket accessed through PolyGram is superior.
If you trade in the UK, you have two primary routes to capitalise on accurate outcome predictions: spread betting (through FCA-licensed financial spread betting operators) and prediction markets (via Polymarket, Betfair Exchange, or Smarkets). Grasping these distinctions matters enormously for structuring your tax position and investment 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). Principal attributes include:
- Leverage: Ranges from 2:1 to 20:1 contingent on the underlying asset category
- Tax-free profits: Spread betting is legally treated as gambling under UK law — returns are exempt from tax, and losses cannot offset other income
- FCA regulated: Comprehensive investor safeguards, mandatory negative balance protection
- Markets: Financial assets (equity indices, currencies, raw materials, company shares) — excludes political or sports wagers
- Bid-ask spread: Embedded cost (usually 1–3 pips on major currency pairs)
What Are Prediction Markets?
Prediction markets enable you to acquire YES/NO binary contracts contingent upon actual-world occurrences. Leading UK-available platforms include:
- Polymarket (via PolyGram): 8,400+ markets, crypto (USDC), ~1% effective fee, regulatory status ambiguous
- Betfair Exchange: 500 markets, GBP, 5% commission, UKGC licensed
- Smarkets: 200 markets, GBP, 2% commission, UKGC licensed
Tax Treatment — The Critical Difference
Spread Betting: Tax-Free
All spread betting returns are completely exempt from Capital Gains Tax and Income Tax in the UK, provided your account is held with an FCA-authorised spread betting provider. This represents one of the most substantial tax benefits available to UK private traders. HMRC's official position endorses this treatment for financial spread betting activities.
Betfair Exchange / Smarkets: Tax-Free
Winnings from UKGC-licensed betting exchanges receive tax-free treatment — categorised as gambling proceeds under the Gambling Act 2005. Consequently, Betfair and Smarkets deliver an optimal combination: prediction market functionality alongside unambiguous tax-free classification.
Polymarket: Tax Uncertain
Polymarket returns do not clearly qualify under either the gambling exemption (lacks UKGC authorisation) or the spread betting exemption (not an FCA-authorised financial spread betting service). HMRC could potentially treat them as CGT or Income Tax liabilities. Consult our UK tax guide.
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-free treatment is essential and regulatory clarity is paramount
- Your strategy focuses on financial price dynamics rather than discrete event outcomes
- You require FCA-mandated negative balance safeguards
Choose Prediction Markets When:
- You possess forecasting skill in particular real-world events (referendums, sports, scientific breakthroughs)
- You prefer a bounded-loss, binary framework (maximum loss equals your stake)
- You need access to markets unavailable through spread betting (geopolitical events, crypto market developments, meteorological outcomes)
- Competitive fee structures relative to conventional betting operators matter to your bottom line
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 strategically important
- Deploy Smarkets or Betfair Exchange for UK-focused events and sports — UKGC-authorised, tax-exempt, sterling-denominated
- Access Polymarket via PolyGram for niche markets absent elsewhere (8,000+ international event contracts) — while managing tax documentation or accepting the regulatory uncertainty
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 platform (FCA-authorised). Both deliver tax-exempt returns under separate UK regulatory regimes. Betfair falls under gambling classification; spread betting falls under financial speculation — both tax-free, overseen by different authorities.
- Can spread betting firms offer political prediction markets?
- Certain providers do — IG Index and Spreadex present election outcome spread bets (e.g. "Conservative seats at 200–210"). These returns are tax-free. Nevertheless, the breadth of coverage remains substantially narrower than Polymarket's 249 UK-centric political contracts.
- Is there a UK prediction market with leverage?
- Not conventionally. Betfair and Smarkets operate on binary mechanics (stake only). Polymarket functions identically (binary). For leveraged event wagering, financial spread betting represents the sole FCA-regulated mechanism — though it exclusively covers financial instrument prices, not discrete event outcomes.