In this guide
Key difference: Spread betting winnings carry no tax liability under UK law. Prediction market returns from crypto platforms such as Polymarket may trigger Capital Gains Tax or Income Tax obligations. For UKGC-authorised, tax-exempt event wagering, Betfair Exchange provides the nearest equivalent. For sheer market selection and minimal fees, Polymarket accessed through PolyGram leads the field.
If you trade in the UK, two primary avenues exist to capitalise on accurate event forecasting: spread betting (through FCA-licensed financial spread betting operators) and prediction markets (through Polymarket, Betfair Exchange, or Smarkets). Grasping these distinctions proves essential for structuring your tax position and refining your trading approach.
What Is Spread Betting in the UK?
The UK's financial spread betting sector is serviced 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 features include:
- Leverage: Commonly ranges from 2:1 to 20:1 based on the asset category
- Tax-free profits: Spread betting sits within the gambling classification under UK law — returns incur no tax, and losses cannot be offset
- FCA regulated: Comprehensive investor safeguards, mandatory negative balance cover
- Markets: Financial assets only (equity indices, currency, commodities, shares) — excludes political or sporting predictions
- Bid-ask spread: Embedded expense (usually 1–3 pips for major currency pairs)
What Are Prediction Markets?
Prediction markets enable you to purchase binary YES/NO contracts tied to tangible real-world occurrences. Leading options accessible from the UK:
- Polymarket (via PolyGram): Over 8,400 markets, USDC-based, roughly 1% total cost, legally ambiguous
- Betfair Exchange: Approximately 500 markets, sterling-denominated, 5% commission, UKGC authorised
- Smarkets: Around 200 markets, GBP, 2% commission, UKGC authorised
Tax Treatment — The Critical Difference
Spread Betting: Tax-Free
Every pound earned through spread betting enjoys exemption from both Capital Gains Tax and Income Tax in the UK, provided your account sits with an FCA-approved spread betting operator. This represents one of the most valuable tax concessions available to UK private traders. HMRC's official position on financial spread betting underscores this advantage.
Betfair Exchange / Smarkets: Tax-Free
Winnings from UKGC-licensed betting exchanges remain untaxed — classified as gambling proceeds under the Gambling Act 2005. Consequently, Betfair and Smarkets deliver an optimal combination: prediction market functionality paired with transparent tax-free treatment.
Polymarket: Tax Uncertain
Polymarket returns sit outside both the gambling exemption (lacks UKGC authorisation) and the spread betting exemption (not an FCA-authorised financial spread betting service). The Revenue may view them as subject to CGT or Income Tax. Review our comprehensive tax resource 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 markets)
- Tax-free status is paramount and you require regulatory certainty
- Your focus lies on trading financial price dynamics 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 (political races, athletic competitions, scientific developments)
- You prefer a limited-loss, binary framework (maximum loss equals your wager)
- You need access to markets unavailable through spread betting (political contests, blockchain events, meteorological outcomes)
- Competitive pricing versus conventional bookies matters to your strategy
Best Combined Approach for UK Traders:
- Maintain an FCA-regulated spread betting account (IG, CMC) for financial instrument positions where leverage and tax-free returns are crucial
- Employ Smarkets or Betfair Exchange for UK political and sports outcomes — UKGC-authorised, tax-exempt, sterling-based
- Access Polymarket via PolyGram for specialised markets beyond traditional offerings (8,000+ international event contracts) — while acknowledging the 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 financial spread betting platforms (FCA-authorised). Both deliver tax-free returns under separate UK legal regimes. 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 feature election outcome spread contracts (e.g. "Conservative seats at 200–210"). These remain tax-free. Nevertheless, breadth is substantially restricted compared to Polymarket's 249 UK-focused political offerings.
- Is there a UK prediction market with leverage?
- Not conventionally. Betfair and Smarkets operate on a binary basis (stake only). Polymarket follows the same binary structure. Leveraged event trading exists solely through financial spread betting under FCA supervision — though it covers only financial instrument valuations, not specific event outcomes.