You backed a horse at 5/1, it won, and then you noticed your winnings were slightly less than you calculated. The settlement note says "Rule 4 deduction: 10p in the pound". A horse was withdrawn from the race, your winnings were adjusted, and the reason is a rule that has governed horse racing betting since the 1950s. This guide explains exactly what Rule 4 is, how the deduction scale works, and when you need to know about it.
Why Rule 4 Exists
When you place a bet on a horse race, the price you get reflects the whole field of competitors. If a heavily fancied rival is subsequently withdrawn from the race, your horse's chances improve — the removed competitor can no longer beat you. If your horse now wins, it won a less competitive race than the one you bet on. Rule 4 compensates the bookmaker for this by reducing your winnings in proportion to the benefit you received from the withdrawal.
The rule is named after Rule 4(c) of the Tattersalls Committee Rules, which have governed betting disputes in British and Irish racing since 1886. It is applied by all bookmakers operating in Ireland and Britain and has been standard practice since 1954.
The Rule 4 Deduction Scale
The deduction percentage is determined by the Starting Price (SP) or the odds of the withdrawn horse at the time of withdrawal. A shorter-priced horse (more likely to win) causes a larger deduction; a longer-priced outsider causes a smaller or zero deduction.
| SP of withdrawn horse | Deduction per £1 profit |
|---|---|
| Odds-on (e.g. 1/2, 4/9) | 75p |
| Evens to 6/5 | 25p |
| 5/4 to 7/4 | 20p |
| 2/1 to 5/2 | 20p |
| 3/1 to 4/1 | 15p |
| 9/2 to 11/2 | 10p |
| 6/1 to 9/1 | 5p |
| 10/1 and above | No deduction |
The deduction is applied to your profit only, not your stake. Your original stake is always returned in full.
Worked Example
You back a horse at 5/1 for €20. Total potential return: €120 (€100 profit + €20 stake). A 3/1 favourite is withdrawn, triggering a 15p in the pound Rule 4 deduction.
Adjusted profit: €100 × (1 − 0.15) = €100 × 0.85 = €85 profit. Your total return: €85 + €20 stake = €105 instead of €120.
When Rule 4 Does NOT Apply
Rule 4 does not apply to ante-post bets: if a horse is withdrawn after you have placed an ante-post wager, the standard rule is that the bet loses outright (not a Rule 4 deduction). This is a fundamental difference between ante-post and day-of-race betting.
Rule 4 also does not apply to Starting Price (SP) bets placed after final declarations, because the SP is calculated after all withdrawals are known. The SP automatically adjusts to reflect the remaining field without needing a Rule 4 correction.
Multiple Deductions and Caps
If two or more horses are withdrawn from the same race, deductions from each can stack. However, the total combined deduction is capped at 75p in the pound. If a very short-priced horse (1/2 favourite, 75p deduction) and a 5/1 shot (5p deduction) both withdraw, you would expect 80p — but it is capped at 75p maximum. 18+ — Gambling Awareness Trust: 1800 753 753, gamblingcare.ie.
Frequently Asked Questions
A Rule 4 deduction is a reduction applied to your winnings when a horse is withdrawn after you bet. It compensates for the improved chance your horse had due to the removal of a competitor.
Yes. Rule 4 deductions apply to both the win and place parts of an each-way bet.
Based on the SP of the withdrawn horse: odds-on (75p), evens to 6/5 (25p), 2/1 to 5/2 (20p), 3/1 to 4/1 (15p), 9/2 to 11/2 (10p), 6/1 to 9/1 (5p), 10/1 and above (no deduction).
Rule 4 does not apply to ante-post bets (non-runners mean the stake is lost outright) or to SP bets placed after declarations (the SP adjusts automatically).
Yes. If multiple horses are withdrawn, deductions from each can be applied, with a maximum combined deduction of 75p in the pound.