A Rule 4 deduction is a reduction applied to winnings on a horse or greyhound bet when a runner is withdrawn after the market has formed but before it can be fully re-priced, so the remaining runners' true chances have improved but the bet was struck at the old odds.
Definition
A Rule 4 deduction is a reduction applied to winnings on a horse or greyhound bet when a runner is withdrawn after the market has formed but before it can be fully re-priced, so the remaining runners' true chances have improved but the bet was struck at the old odds. The deduction is taken from net winnings (not the stake) and scaled to the withdrawn runner's odds at the time it was pulled: the shorter the non-runner's price (the more likely it was to win), the larger the deduction, on a published sliding scale.
Rule 4 applies to bets placed at fixed odds before a withdrawal; bets taken at SP (starting price) or after the market is re-formed are not affected. It is a standard settlement rule across licensed bookmakers, derived from a long-standing industry tariff, and the exact scale is in each operator's terms.
In context
For affiliates, Rule 4 is a racing-specific term that belongs in any horse-racing betting guide and in glossary coverage, because a deduction from a winning bet with no obvious explanation is a common source of confusion and complaint. Clear content states what triggers it (a runner withdrawn after the bet, at fixed odds), that it comes off net winnings not the stake, and shows the sliding scale with an example so a reader can see how a short-priced non-runner produces a bigger deduction than a longshot.
The framing should be neutral and educational: Rule 4 is a fairness mechanism, not an operator penalty — without it, a bet struck before a strong horse was pulled would be overpriced relative to the real race. Good content notes that betting at SP avoids Rule 4, that the deduction interacts with each-way and dead-heat settlement, and that the exact scale and any minimum threshold are in the operator's terms and can differ slightly.
Standard compliance applies: age-gating, responsible-gambling messaging, licensed operators only. The goal is to help readers understand a legitimate settlement rule and what they will actually be paid, not to drive additional betting.
Worked example
An affiliate's racing guide explains Rule 4 with an example: a 10 win bet at 5.0 (40 net winnings) is affected when a 3.0-priced rival is withdrawn, triggering a deduction of around 30 pence in the pound, so net winnings become about 28 and the return about 38. It notes betting at SP avoids this and links the each-way and dead-heat rules.
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