You back a horse, it wins, and your payout is less than you expected. No error, no dispute — just a Rule 4 deduction that reduced your winnings. For bettors who have not encountered this before, it can feel unexplained. For bettors who understand it, it is a straightforward industry-standard adjustment with a published deduction table.
This guide explains what Rule 4 deductions are, why they exist, exactly how the deduction is calculated, and what happens when multiple horses are withdrawn from the same race.
What Is a Rule 4 Deduction?
A Rule 4 deduction is a reduction applied to winnings when a competitor is withdrawn from a race after bets have been placed on that race.
The rule takes its name from Rule 4(c) of the Tattersalls Rules on Betting — the industry-standard framework governing UK horse racing settlement that virtually all licensed bookmakers follow.
Why the deduction exists:
When a horse is withdrawn, every remaining runner’s probability of winning increases — simply because there is one fewer competitor. If you backed a horse at 6/1 in a six-runner field and the 2/1 favourite is subsequently withdrawn, your horse’s chances of winning are now meaningfully better than they were when you placed the bet. Without a deduction, you would collect winnings calculated at 6/1 odds that reflected a six-runner field, while benefiting from the improved probability of a five-runner field.
The Rule 4 deduction adjusts your return to reflect what your odds would have been had the withdrawn horse never been in the race at the time of betting. It is not a penalty — it is a recalibration of the bet’s expected value.
When Rule 4 Deductions Apply
Rule 4 deductions apply when:
- A horse (or other competitor) is withdrawn after the market has opened and after bets have been placed
- The withdrawal occurs before the race starts — not during it
- The withdrawn horse had odds short enough to affect the field’s probabilities meaningfully (withdrawals at odds longer than 14/1 / 15.00 decimal carry no deduction — see table below)
Most common scenarios:
- A horse is withdrawn on race morning due to injury, illness, or ground conditions
- A late non-runner is declared shortly before the off
- A horse fails the pre-race veterinary inspection
Rule 4 deductions are most commonly encountered in horse racing but also apply in golf tournaments and occasionally in other multi-runner events where bookmakers have taken bets on a specific starting field.
The Rule 4 Deduction Table
The amount deducted is determined by the price of the withdrawn horse at the time of its withdrawal. The shorter the price — meaning the more likely the horse was to win — the larger the deduction, because the remaining field benefits more from its absence.
All deductions are expressed as pence per £1 of winnings (not per £1 staked).
| Withdrawn Horse Price (Fractional) | Withdrawn Horse Price (Decimal) | Deduction Per £1 Won |
|---|---|---|
| 1/9 or shorter | 1.11 or shorter | 90p |
| 2/11 to 2/17 | 1.18 to 1.12 | 85p |
| 1/4 to 1/5 | 1.25 to 1.20 | 80p |
| 3/10 to 2/7 | 1.30 to 1.29 | 75p |
| 2/5 to 1/3 | 1.40 to 1.33 | 70p |
| 8/15 to 4/9 | 1.53 to 1.45 | 65p |
| 8/13 to 4/7 | 1.62 to 1.57 | 60p |
| 4/5 to 4/6 | 1.80 to 1.66 | 55p |
| 20/21 to 5/6 | 1.95 to 1.83 | 50p |
| Evens to 6/5 | 2.00 to 2.20 | 45p |
| 5/4 to 6/4 | 2.25 to 2.50 | 40p |
| 8/5 to 7/4 | 2.60 to 2.75 | 35p |
| 9/5 to 9/4 | 2.80 to 3.25 | 30p |
| 12/5 to 3/1 | 3.40 to 4.00 | 25p |
| 16/5 to 4/1 | 4.20 to 5.00 | 20p |
| 9/2 to 11/2 | 5.50 to 6.50 | 15p |
| 6/1 to 9/1 | 7.00 to 10.00 | 10p |
| 10/1 to 14/1 | 11.00 to 15.00 | 5p |
| Over 14/1 | Over 15.00 | No deduction |
The deduction applies to your winnings, not your stake. Your stake is always returned in full on a winning bet. The deduction reduces only the profit element.
Worked Example: Single Rule 4 Deduction
The race: Six runners. You back Horse A at 6/1 with a £20 stake.
What you expect to receive (no deduction): £20 stake × 6/1 = £120 winnings + £20 stake returned = £140 total
What happens: Horse B, the race favourite at 2/1, is withdrawn as a non-runner before the race begins.
Applying the deduction:
- A 2/1 withdrawal falls in the 9/5 to 9/4 band → 30p deduction per £1 won
- Your winnings were £120
- Deduction: £120 × 0.30 = £36
- Adjusted winnings: £120 − £36 = £84
- Your stake (£20) is returned in full
- Total payout: £84 + £20 = £104
Without the deduction, you would have collected £140 on odds set for a six-runner race. With the deduction, you receive £104 — the adjusted return that reflects what your 6/1 odds would have been in a five-runner field without the favourite.
Worked Example: Multiple Rule 4 Deductions
More than one Rule 4 deduction can apply if more than one competitor is withdrawn after your bet was placed. Each withdrawal is assessed separately and the deductions are combined.
The maximum combined deduction is 90p per £1 won — even if multiple withdrawals would mathematically exceed this figure.
Example:
You back Horse C at 8/1 with a £10 stake in a ten-runner race.
Two horses are subsequently withdrawn:
- Horse D at 2/1 → 30p deduction per £1
- Horse E at 3/1 → 25p deduction per £1
Combined deduction: 30p + 25p = 55p per £1 won
Your calculation:
- Expected winnings: £10 × 8 = £80
- Deduction: £80 × 0.55 = £44
- Adjusted winnings: £80 − £44 = £36
- Stake returned: £10
- Total payout: £46
Example with cap applied:
If combined deductions exceed 90p per £1, the 90p cap applies.
- Horse F at 1/5 → 80p deduction
- Horse G at 2/5 → 70p deduction
- Combined = 150p — capped at 90p
In this scenario, you retain 10p profit per £1 won regardless of how short the withdrawn horses were priced.
Rule 4 and Each Way Bets
Rule 4 deductions apply to both the win and place parts of an each way bet. The deduction is calculated separately on each portion of the return and applied to the winnings (not the stake) on each.
If a horse is withdrawn and the reduced field means the place terms also change (for example, a race dropping below the threshold for three-place terms), the revised place terms apply alongside the Rule 4 deduction. Your bookmaker will apply both adjustments automatically on settlement.
Rule 4 and SP (Starting Price) Bets
If you placed your bet at the bookmaker’s Starting Price rather than a fixed early price, your bet will have been placed at odds that already reflect the final field — i.e., the price you received was set after any withdrawals were already known.
Rule 4 deductions typically do not apply to SP bets in this circumstance because the Starting Price is calculated on the actual field that ran. However, in some cases — particularly where a withdrawal occurs after the market has opened for live trading but before the official SP is returned — a deduction may still apply. Check your bookmaker’s specific SP settlement rules if you are unsure.
Rule 4 in Golf Betting
Golf is the other sport where Rule 4 deductions are frequently encountered. When a player withdraws from a tournament after betting markets have opened — due to injury, illness, or personal reasons — Rule 4 deductions apply to any remaining bets on the field.
Golf-specific considerations:
- Withdrawals during a round (after the player has teed off) are treated differently from pre-tournament non-starters. Mid-round withdrawals typically result in void bets on the withdrawn player rather than triggering a Rule 4 on other bets — but this varies by bookmaker. Check the settlement rules before placing outright tournament bets.
- In large fields (60–80 players), even a significant withdrawal may trigger only a modest deduction, as no single player at 20/1+ in a 70-player field significantly affects the remaining probabilities.
How to Check Whether a Rule 4 Deduction Was Applied Correctly
If your winning return is lower than expected, check your bookmaker’s settled bet details. Most UKGC-licensed bookmakers now display the applied Rule 4 deduction as a separate line in the settlement breakdown — showing the withdrawn horse’s price, the deduction percentage, and the adjusted return.
Steps to verify:
- Find the settled bet in your account’s bet history
- Check whether a Rule 4 deduction is listed alongside the return
- Identify the withdrawn horse and its price at the time of withdrawal
- Cross-reference against the deduction table above to confirm the correct percentage was applied
- Recalculate: (original winnings) × (1 − deduction percentage) + stake = expected payout
If the calculation does not match and you believe an error has been made, contact your bookmaker’s customer support with the settled bet reference. UKGC-licensed operators must provide transparent settlement information and have an approved ADR (Alternative Dispute Resolution) provider for unresolved disputes.
Frequently Asked Questions
Does Rule 4 apply to ante-post bets?
Generally, no. Ante-post bets — placed well before the race on future events — typically operate under different terms that accept non-runner risk as part of the bet. Many ante-post bets include a “non-runner no bet” clause that voids the bet entirely if your selection does not run, rather than applying a Rule 4 deduction. Check the specific ante-post terms before placing, as this varies by bookmaker and event type.
What if the horse I backed is the one withdrawn?
If the horse you backed is the non-runner, your bet is void and your stake is returned in full. Rule 4 deductions apply to the remaining bets on the field — not to the bet on the withdrawn horse itself.
Does Rule 4 apply to exchange bets on Betfair?
Betfair Exchange handles non-runners differently from traditional bookmakers. When a horse is withdrawn, the exchange recalculates the market using a reduction factor rather than a flat Rule 4 deduction from the Tattersalls table. The effective reduction is similar in principle but calculated dynamically based on the exchange’s own odds at the time of withdrawal rather than the fixed table above. The Betfair Exchange website publishes its reduction factor policy in its rules section.
Is there a maximum Rule 4 deduction?
Yes — 90p per £1 won, regardless of how many horses are withdrawn or how short their prices were. You always retain at least 10p profit per £1 won on a successful bet, even in the most extreme withdrawal scenarios.
Why does the deduction apply to winnings rather than stake?
Because the deduction adjusts for the change in your horse’s probability of winning — which affects the profit element of the bet, not the return of your original investment. Your stake represents what you risked; the winnings represent the profit from the improved probability. Only the profit element is recalibrated.
Can Rule 4 deductions be disputed?
Yes, if you believe the wrong deduction percentage was applied or the wrong withdrawal price was used. Contact your bookmaker’s customer support with the specific bet reference. If the dispute is unresolved, UKGC-licensed bookmakers must refer you to their approved ADR provider, whose decision is binding on the operator.
Sources: Tattersalls Rules on Betting; British Horseracing Authority; UK Gambling Commission. All external links verified as of March 2026.