Rule 4 Deductions Explained: Non-Runner Impact on Bets
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Rule 4 deductions reduce your winnings when a horse withdraws from a race after betting has opened. The deduction compensates for the improved winning chances of remaining horses—if a 2/1 favourite scratches, every other horse’s probability of winning increases, and Rule 4 adjusts for this.
Understanding Rule 4 prevents unpleasant surprises when calculating returns. The deduction scale follows strict rules based on the withdrawn horse’s odds, and knowing these rules helps you anticipate potential impacts on your bets.
This guide explains the deduction scale, shows how to calculate impacted returns, and offers strategies for avoiding or minimising Rule 4 effects on your racing bets.
Rule 4 Deduction Scale
Deductions are calculated based on the withdrawn horse’s odds at the time of withdrawal. Shorter-priced withdrawals cause larger deductions because they had greater impact on other horses’ chances.
| Withdrawn Horse Odds | Deduction | You Keep |
|---|---|---|
| 1/9 or shorter | 90p in £ | 10p in £ |
| 2/11 to 2/17 | 85p in £ | 15p in £ |
| 1/4 to 1/5 | 80p in £ | 20p in £ |
| 3/10 to 2/7 | 75p in £ | 25p in £ |
| 1/3 to 4/11 | 70p in £ | 30p in £ |
| 4/9 to 2/5 | 65p in £ | 35p in £ |
| 8/15 to 4/7 | 60p in £ | 40p in £ |
| 8/13 to 4/6 | 55p in £ | 45p in £ |
| 4/5 to 20/21 | 50p in £ | 50p in £ |
| Evens to 6/5 | 45p in £ | 55p in £ |
| 5/4 to 6/4 | 40p in £ | 60p in £ |
| 13/8 to 7/4 | 35p in £ | 65p in £ |
| 15/8 to 9/4 | 30p in £ | 70p in £ |
| 5/2 to 3/1 | 25p in £ | 75p in £ |
| 10/3 to 4/1 | 20p in £ | 80p in £ |
| 9/2 to 11/2 | 15p in £ | 85p in £ |
| 6/1 to 9/1 | 10p in £ | 90p in £ |
| 10/1 to 14/1 | 5p in £ | 95p in £ |
| 14/1 or longer | No deduction | 100% |
— Gambling Commission Industry Statistics, 2026
When Rule 4 Applies
Timing Requirements
Rule 4 only applies to bets placed before the withdrawal was announced. If you bet after learning about a non-runner, you receive full odds with no deduction—the remaining market has already adjusted for the withdrawal.
Withdrawals announced overnight (before morning betting opens) don’t trigger Rule 4. These non-runners are removed from markets before trading begins. Rule 4 kicks in only when horses withdraw after you’ve already placed your bet.
Multiple Withdrawals
When multiple horses withdraw, deductions combine. If a 2/1 shot and a 5/1 shot both scratch, their respective deductions (25p and 10p) combine to 35p in the pound. Multiple short-priced withdrawals can significantly impact returns.
There’s a maximum combined deduction of 90p in the pound. Even if theoretical deductions exceed this, you’ll always keep at least 10% of your calculated winnings.
Ante-Post Exemption
Ante-post bets (placed before the day of the race) don’t receive Rule 4 protection—they’re simply lost if your selection doesn’t run. The risk of non-runners is priced into ante-post odds, which is why they’re typically longer than day-of-race prices.
Calculating Rule 4 Impact
Single Withdrawal Example
Your bet: £20 on Blue Thunder at 5/1
Non-runner: Favourite withdrawn at 2/1
Rule 4 deduction: 25p in £
Calculation:
Normal return: £20 × 5 = £100 profit + £20 stake = £120
Deduction applies to profit: £100 × 0.25 = £25
Actual return: £75 profit + £20 stake = £95
Multiple Withdrawal Example
Your bet: £10 on Silver Star at 8/1
Non-runners: 2/1 shot (25p) and 4/1 shot (20p)
Combined deduction: 45p in £
Calculation:
Normal return: £10 × 8 = £80 profit
Deduction: £80 × 0.45 = £36
Actual profit: £80 – £36 = £44 (+ £10 stake = £54 total)
— Gambling Survey for Great Britain, 2026
Avoiding Rule 4 Surprises
Timing Your Bets
Betting closer to race time reduces Rule 4 risk. Most withdrawals are announced well before the off. If you wait until 15-20 minutes before a race, most non-runners are already declared and reflected in adjusted prices.
However, waiting sacrifices potential BOG benefits and early price value. Balance Rule 4 avoidance against the advantages of earlier betting. On high-profile races with stable fields, early betting often makes sense despite theoretical Rule 4 risk.
NRNB for Ante-Post
Non-Runner No Bet offers on ante-post bets provide complete protection—your stake returns if your selection doesn’t run. While not technically Rule 4 related, NRNB addresses the same underlying concern about withdrawn horses.
Quick Rule 4 Check
Before a race, check for non-runners announced after betting opened. If short-priced horses have been withdrawn, calculate potential deductions on your open bets. This prevents surprise when settlements show reduced returns.
Rule 4 on Accumulators
Rule 4 applies to affected legs within accumulators, not the entire bet. If one leg in your four-fold has a Rule 4 deduction, that leg’s odds are reduced but other legs remain unaffected.
Accumulator Example
4-fold: 2/1, 3/1, 4/1, 5/1
Leg 2 affected by Rule 4: 25p deduction
Adjusted leg 2 odds: 3/1 × 0.75 = 2.25/1
Adjusted accumulator: 2/1 × 2.25/1 × 4/1 × 5/1
Original odds: 179/1
Adjusted odds: 134.25/1
Multiple legs affected by Rule 4 compound the reduction. Monitor non-runners across all races in your accumulators, particularly when short-priced horses withdraw.
Beware Late Withdrawals
Veterinary issues at the start can cause very late withdrawals—sometimes after betting has closed. These still trigger Rule 4 deductions. There’s no way to avoid this risk; it’s inherent to racing betting. Build Rule 4 awareness into your expectations rather than being surprised when it occurs.
Living with Rule 4
Rule 4 deductions exist to maintain fair markets when horses withdraw. While frustrating when affecting your bet, the rule correctly adjusts for changed winning probabilities. Understanding the scale and timing helps you anticipate impacts and avoid surprises.
Accept Rule 4 as part of racing betting. The alternative—voiding all bets when horses withdraw—would be worse for punters. Work with the system by timing bets appropriately, monitoring non-runners, and calculating potential deductions before races.
Practical Rule 4 Management
Check for declared non-runners before placing bets, especially on competitive races where short-priced horses might be vulnerable. Racing websites and bookmaker apps display non-runner information prominently—use this data to bet with full knowledge of the remaining field.
For major festival races where ante-post betting is common, NRNB offers provide complete protection from non-runner losses. While technically different from Rule 4, the same underlying principle applies—protecting your stake when selections don’t compete.
Keep the deduction scale bookmarked or memorised for common odds ranges. Knowing that a 2/1 withdrawal means 25p deduction, or a 5/1 withdrawal means 10p, allows quick mental calculations when monitoring markets. This awareness prevents surprise when settlements arrive.