Rule 4 deductions in UK racing: the full reference
When and how Rule 4 deductions apply in UK horse racing. The Tattersalls deduction scale, worked examples, multiple non-runners, and where Rule 4 doesn't apply.
Rule 4 is the Tattersalls Committee's rule that lets UK bookmakers reduce the payout on winning bets when a non-runner is withdrawn from a race after the bets were placed but before the race begins. It's the single biggest reason a winning racing bet sometimes settles at less than the price you took.
When Rule 4 applies
Three conditions all need to be true for a Rule 4 deduction:
- You placed a bet on a horse race (or sometimes a greyhound race) at fixed odds
- A different horse from the same race was withdrawn after your bet was placed
- The withdrawal happened too late for the bookmaker to reform the market — typically inside 15 minutes of the off
If the withdrawal happens early enough for the bookmaker to reform their market and re-issue prices, Rule 4 doesn't apply — the market is just re-priced. If it happens too late, your existing bet stays live but the payout is deducted.
The Tattersalls Rule 4 deduction scale
The deduction depends on the price of the withdrawn horse. The shorter the price of the non-runner, the bigger the deduction — because a short-priced withdrawal had a higher implied probability of winning, which means the remaining horses' true probabilities all shift up.
| Decimal odds of non-runner | Fractional equivalent | Deduction per £1 of winnings |
|---|---|---|
| 1.11 or shorter | 1/9 or shorter | 90p |
| 1.12 to 1.18 | 2/11 to 2/9 | 85p |
| 1.19 to 1.25 | 1/4 to 1/5 | 80p |
| 1.26 to 1.33 | 2/7 to 1/3 | 75p |
| 1.34 to 1.40 | 4/11 to 2/5 | 70p |
| 1.41 to 1.50 | 4/9 to 1/2 | 65p |
| 1.51 to 1.66 | 4/7 to 4/6 | 55p |
| 1.67 to 1.80 | 8/13 to 4/5 | 45p |
| 1.81 to 2.00 | 4/5 to evens | 40p |
| 2.01 to 2.20 | evens to 6/5 | 35p |
| 2.21 to 2.62 | 6/5 to 13/8 | 30p |
| 2.63 to 3.00 | 13/8 to 2/1 | 25p |
| 3.01 to 3.75 | 2/1 to 11/4 | 20p |
| 3.76 to 5.50 | 11/4 to 9/2 | 15p |
| 5.51 to 11.00 | 9/2 to 10/1 | 10p |
| 11.01 to 15.00 | 10/1 to 14/1 | 5p |
| 15.01 or longer | 14/1 or longer | No deduction |
Worked example
You back Hot Favourite at 3.00 (2/1) in a 10-runner handicap with a £50 stake. Twelve minutes before the off, Another Runner — priced at 1.50 (1/2) — is withdrawn from the race. Your bet stays live, but Rule 4 applies because the non-runner was inside the 15-minute window.
Settlement maths:
- Non-runner's odds: 1.50 → Rule 4 deduction band: 65p per £1 of winnings
- Your bet: £50 at 3.00
- Hot Favourite wins. Gross winnings (profit only, not stake): £50 × (3.00 − 1) = £100
- Rule 4 deduction: £100 × 0.65 = £65
- Net winnings: £100 − £65 = £35
- Total return: £50 stake + £35 net winnings = £85
Without Rule 4 you'd have returned £150. The deduction is real and meaningful.
Why the deduction makes sense (the bookmaker's case)
When Another Runner was in the market, the bookmaker priced Hot Favourite at 3.00 on the basis of competing against the full field. Removing a short-priced rival makes Hot Favourite a more likely winner — the bookmaker's liability went up. Rule 4 reduces the payout to reflect the new, shorter true odds Hot Favourite should have carried in the smaller field.
In other words: the price you took priced in Another Runner as competition. Without that competition, the fair price is shorter. Rule 4 enforces a settlement closer to the fair price.
Multiple non-runners
If more than one horse is withdrawn after your bet, the deductions are not added in absolute terms — they're combined multiplicatively. The combined deduction is calculated by multiplying the surviving fractions:
combined deduction = 1 − [(1 − r₁) × (1 − r₂) × …]
Where r₁, r₂ etc. are the individual deductions. Example: two non-runners at 25p and 20p deductions. Combined: 1 − (0.75 × 0.80) = 0.40, or 40p in the pound. The total deduction cap is generally 90p in the pound.
Where Rule 4 doesn't apply
- Ante-post bets — the price was taken weeks or months before the race, so non-runner withdrawals don't trigger Rule 4. Ante-post bets are usually void if the horse doesn't run, with stake returned.
- Greyhound races — sometimes apply a similar mechanism, sometimes not, depending on the bookmaker's rules.
- Markets settled before the non-runner — if you cashed out before the withdrawal, no deduction applies retrospectively.
- BOG (Best Odds Guaranteed) doesn't protect against Rule 4. BOG protects against price drift, not non-runner deductions.
Rule 4 is sometimes confusing for newcomers because it feels like the bookmaker is unilaterally cutting your winnings. The maths is fair — it reflects the actual market change. For the wider context on how bookmakers price markets and where their margin comes from, the deep dive on bookmaker overround is the foundational reference.