In this guide
Key difference: Under UK legislation, spread betting returns enjoy complete tax exemption. Prediction market returns sourced from decentralised platforms such as Polymarket may trigger Capital Gains Tax or Income Tax obligations. For tax-exempt event wagering with regulatory oversight, Betfair Exchange provides the closest equivalent. For breadth of available contracts and minimal transaction costs, Polymarket accessed through PolyGram remains superior.
In the United Kingdom, traders pursuing profit from accurate outcome forecasting have two primary channels: spread betting (through FCA-licensed financial spread betting operators) and prediction markets (through Polymarket, Betfair Exchange, or Smarkets). Distinguishing between these mechanisms is essential for compliance and optimal tax structuring.
What Is Spread Betting in the UK?
The UK spread betting sector comprises FCA-authorised providers including IG, CMC Markets, and Spreadex. Traders stake per-point sums on price fluctuations in financial assets (FTSE 100, currency pairs, individual equities). Principal attributes include:
- Leverage: Commonly ranges from 2:1 to 20:1 based on underlying asset category
- Tax-free profits: Spread betting qualifies as gambling under UK law — resulting gains incur no tax liability, whilst losses cannot be offset
- FCA regulated: Comprehensive investor safeguards, mandatory negative balance protection
- Markets: Financial assets (stock indices, currency markets, raw materials, equity securities) — excludes political or sporting event contracts
- Bid-ask spread: Embedded transaction expense (ordinarily 1–3 pips on major currency pairs)
What Are Prediction Markets?
Prediction markets enable participants to acquire YES/NO outcome contracts on actual real-world occurrences. Prominent UK-accessible platforms comprise:
- Polymarket (via PolyGram): Over 8,400 markets, blockchain-based USDC, approximately 1% net cost, regulatory status ambiguous
- Betfair Exchange: Approximately 500 markets, GBP denominated, 5% commission structure, UKGC authorised
- Smarkets: Roughly 200 markets, GBP denominated, 2% commission structure, UKGC authorised
Tax Treatment — The Critical Difference
Spread Betting: Tax-Free
Under UK legislation, all spread betting returns receive complete exemption from Capital Gains Tax and Income Tax when conducted through an FCA-licensed spread betting provider. This represents one of the most advantageous tax positions available to UK retail market participants. HMRC's published materials substantiate this treatment regarding financial spread betting activities.
Betfair Exchange / Smarkets: Tax-Free
Returns from UKGC-authorised betting exchanges are similarly exempt from taxation — classified as gambling income under the Gambling Act 2005. This positions Betfair and Smarkets as optimal hybrids: prediction market functionality combined with unambiguous tax-exempt status.
Polymarket: Tax Uncertain
Polymarket returns do not neatly align with either the gambling exemption (absent UKGC authorisation) or the spread betting exemption (lacking FCA financial spread betting classification). HMRC assessment may classify such returns as Capital Gains Tax or Income Tax events. 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 positions in financial assets (FTSE 100, currency markets)
- Tax-exempt treatment is paramount and regulatory certainty is required
- Your trading focus centres on financial price dynamics rather than discrete occurrences
- You require FCA-mandated negative balance safeguards
Choose Prediction Markets When:
- You possess demonstrable forecasting capability for particular real-world events (electoral contests, athletic competitions, scientific developments)
- You prefer a capped-loss, binary framework (maximum loss equals initial stake)
- You require access to contract categories unavailable through spread betting platforms (electoral outcomes, blockchain developments, meteorological events)
- Reduced transaction costs relative to conventional wagering operators matter significantly
Best Combined Approach for UK Traders:
- Maintain an FCA-authorised spread betting account (IG, CMC) for financial asset exposure where leverage and tax-exempt status are strategically important
- Employ Smarkets or Betfair Exchange for UK electoral and sporting contracts — UKGC-regulated, tax-exempt, GBP-denominated
- Access Polymarket via PolyGram for contract categories absent from other venues (8,000+ international event derivatives) — whilst acknowledging tax treatment 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-regulated), distinct from financial spread betting platforms (FCA-regulated). Both mechanisms deliver tax-exempt 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 operators do — IG Index and Spreadex provide election outcome spread contracts (e.g. "Conservative seats at 200–210"). These transactions remain tax-exempt. Nevertheless, market breadth remains substantially constrained relative to Polymarket's 249 UK-focused electoral contracts.
- Is there a UK prediction market with leverage?
- Conventionally, no. Betfair and Smarkets operate on binary structures (stake-only basis). Polymarket similarly functions as binary. Leveraged event trading remains accessible exclusively through FCA-regulated financial spread betting — though this channel covers only financial instrument valuations, not discrete event outcomes.