Rule 4 explained: how UK horse racing deductions work

Rule 4 is a deduction UK bookmakers apply to winning bets on horse (and greyhound) racing when a runner is withdrawn after you've placed your bet. It reduces your winnings, not your stake, because a withdrawal changes the real chances of everyone left in the race — without an adjustment, backers of the remaining runners would be paid at odds that no longer reflect the true risk the bookmaker took on. The size of the deduction depends on the withdrawn runner's odds, as set out in the official scale below.

Key facts

• Rule 4 comes from Tattersalls Committee's official Rules on Betting, first issued in 1886 and last revised in 2010 — not an individual bookmaker's own invention, though bookmakers apply it.
• The deduction only ever reduces winnings, never your stake. Your original stake is always returned in full on a winning bet; Rule 4(C) reduces the profit portion only, in pence per pound.
• The size of the deduction depends on the withdrawn horse's odds at the moment it was withdrawn — the shorter (more fancied) the withdrawn horse, the bigger the deduction, because a strong fancy leaving the race improves everyone else's real chances the most.
• No deduction applies at all if the withdrawn horse was 14/1 or bigger. A long-shot withdrawal is judged not to meaningfully change the market.

The official deduction scale

Per Tattersalls Committee Rule 4(C), the deduction depends on the withdrawn horse's odds at the time of the official withdrawal notification:

Shorter odds mean a bigger deduction, tapering to zero above 14/1 — a selected subset of the full table above.

If more than one horse is withdrawn, each qualifying withdrawal's deduction is added together — but the combined total can never exceed 90p in the pound.

Worked example

You back a horse at 5/1 to win £50 on a £10 stake. Before the race, a 15/8 favourite is withdrawn. 15/8 falls in the "9/5 to 9/4" band, so a 30p deduction applies. Your £50 profit is reduced by 30% to £35, and your £10 stake is still returned in full — a total return of £45 instead of £60.

When Rule 4 doesn't apply

• Losing bets are never affected. Rule 4 only reduces the profit on a winning bet — it has no effect if your selection didn't win.
• Bets placed after the withdrawal, at the reformed market's new odds, are settled on those new odds — the deduction only corrects bets struck before the market adjusted.
• A genuine "walkover" (only one horse left able to run) voids every bet on the race entirely, rather than applying a Rule 4 deduction.

Why the rule exists, not just how it works

A race's odds reflect every declared runner's chance of winning. Remove a strong fancy and the true chance of every remaining horse goes up — paying out at the old, pre-withdrawal odds would hand backers a better price than the market ever actually supported. Rule 4 corrects for exactly that shift, nothing more.

The UK Gambling Commission has taken enforcement action over Rule 4 being misapplied for commercial gain rather than genuine market correction: in 2018 it found a Ladbrokes trader had deliberately shortened a withdrawn horse's quoted price specifically to trigger a bigger deduction on customers' winnings, and required remedial changes (immediate market suspension on withdrawal notice, staff retraining, audited trading-team calls) as a result.

Common misconceptions

• "Rule 4 is a bookmaker trick to avoid paying out." It's an industry-standard rule set by Tattersalls Committee, applied by every UK bookmaker on qualifying races — not a discretionary reduction any single operator invented.
• "My stake gets reduced too." No — only the winnings/profit portion is reduced; your stake is always paid back in full on a winning bet.
• "Any withdrawal triggers a deduction." Only withdrawals at odds of 14/1 or shorter trigger a deduction at all — longer-priced withdrawals carry no Rule 4 adjustment.

Rule 4, dead heat or void bet — which applies?

These three horse-racing settlement rules get confused because they can all change what a winning-looking bet actually pays out, but they cover different situations:

Only one of these normally applies to a given bet — a horse that's withdrawn is covered by Rule 4, not a dead heat or a void, unless the specific circumstances of the withdrawal itself meet the separate criteria for voiding a bet (see our void bets guide).

Related content

See our guides to each-way betting and ante-post betting for other horse-racing settlement mechanics, dead heat betting for what happens when two horses finish level rather than one being withdrawn, and void bets for when a bet is cancelled outright. For the full picture of horse-racing-specific betting concepts, see our horse racing betting hub.