What Is Rule 4?
Rule 4 (formally Tattersalls' Rule 4(c)) is a standard bookmaker rule that applies when a horse is withdrawn from a race after you've placed your bet but before the race starts. Because a non-runner's removal typically improves the chances of every remaining horse, a deduction is applied to winning bets on the remaining runners to reflect that improved chance — even though your horse still won or placed as normal.
This catches a lot of punters off guard: you back a winner at 5/1, the bet settles, and the actual payout is smaller than 5/1 would suggest, because a deduction was applied for an unrelated horse withdrawn earlier in the day.
Why the Deduction Exists
Odds are priced based on the full field of runners. If a fancied horse is withdrawn shortly before the race, the remaining horses' true chances of winning all increase — the market simply hasn't had time to fully reprice every remaining runner's odds to reflect the smaller field. Rule 4 corrects for this by deducting a percentage from winning bets on the remaining runners, roughly equivalent to the improved chance they gained from the withdrawal.
How the Deduction Scale Works
The deduction percentage is based on the industry starting price (SP) of the withdrawn horse at the time it was taken out — the shorter the withdrawn horse's odds, the bigger the deduction, because a well-fancied horse's absence improves the field's chances more than a rank outsider's withdrawal would. Typical Rule 4 deduction bands (these can vary slightly by bookmaker):
- Withdrawn horse odds of 1/9 or shorter: 90p in the £1 deducted
- 2/11 to 2/17: 85p in the £1
- 1/4 to 1/5: 80p in the £1
- 3/10 to 2/5: 75p in the £1
- 8/15 to 4/5: 70p in the £1
- 20/21 to 6/5: 65p in the £1
- Around evens to 6/4: 60p in the £1
- 7/4 to 9/4: 55p in the £1
- 5/2 to 3/1: 50p in the £1
- 10/3 to 4/1: 45p in the £1
- 9/2 to 11/2: 40p in the £1
- 6/1 to 9/1: 30p in the £1
- 10/1 to 14/1: 20p in the £1
- Longer than 14/1: no deduction, or a small nominal deduction depending on the bookmaker
The deduction applies only to your winnings (the profit portion), never to your original stake, and only applies to bets settled at winning odds — a losing bet is unaffected by Rule 4.
A Worked Example
You back a horse at 5/1 for £10. Before the race, a well-fancied runner priced at 2/1 is withdrawn, triggering a 50p in the £1 deduction. Your horse wins. Normally you'd collect £50 profit + £10 stake = £60. With the 50p deduction applied to the £50 profit, you instead receive £25 profit + £10 stake = £35 total.
Rule 4 vs Ante-Post Non-Runner Risk
It's worth distinguishing Rule 4 from the non-runner rule that applies to ante-post bets. Rule 4 applies to bets placed close to race time (including day-of-race prices), and reduces your winnings rather than voiding the bet outright — your stake is always safe if your horse actually wins or places. Ante-post non-runner risk is far more severe: if your ante-post selection doesn't run at all, you lose your entire stake, with no deduction-based partial payout involved.
Does Rule 4 Apply to Multiples?
Yes. Rule 4 deductions apply to each individual leg of a multiple bet affected by a withdrawal, which compounds across doubles, trebles and system bets like a Lucky 15 or Yankee. If two of the legs in your accumulator were each subject to separate Rule 4 deductions on different days or meetings, both deductions apply, multiplying together to reduce your overall return. This is worth factoring in when using the bet calculator to estimate potential multiple-bet returns ahead of time — the figures shown assume no Rule 4 deductions, since these can only be known once withdrawals are confirmed close to race time.