What is Rule 4?

Rule 4 is a bookmaker deduction applied to winnings when a horse is withdrawn from a race after you have placed your bet, reducing your payout to reflect the shorter field and the fact that the remaining runners now have a better chance of winning. Named after the old Tattersalls betting rule, it is charged as pennies-in-the-pound taken off net winnings, scaled to the withdrawn horse's odds at the time it was pulled out. The shorter the withdrawn horse's price, the larger the deduction, because a strong contender leaving the race improves everyone else's chances the most. A published Rule 4 table sets the rate: a non-runner at 1/1 (2.00) triggers a 50p-in-the-pound deduction, one at 4/1 (5.00) around 20p, and a longshot at 20/1 or bigger usually attracts nothing. Worked example: you back a horse at 6/1 for a £20 win stake. Before the off, the second favourite is withdrawn at odds of 3/1 (4.00), which sits in the 25p-in-the-pound band. Your winnings would have been £120, but Rule 4 removes 25% of that: £120 minus £30 leaves £90 profit. Your £20 stake is still returned on top, so you collect £110 rather than £140. If the horse loses, no deduction applies. Practical context: Rule 4 is standard across UK and Irish racing and applies whether you bet at fixed odds pre-race or take an early price, so a headline payout can shrink at settlement. The common mistake is assuming a withdrawn rival has no effect on your slip. Compare with each-way, ante-post, dead-heat and void-bet rules.