Rule 4 Deductions in Horse Racing: What Happens When a Horse Withdraws

The Adjustment You Did Not Ask For

You back a horse at 5/1 in a seven-runner race, feeling confident about your selection. An hour before the off, the favourite is withdrawn. The race now has six runners instead of seven, and the remaining horses are effectively better value than the market had priced them — because the horse most likely to beat yours is no longer in the field. Your 5/1 suddenly looks generous. The problem is, you took that price when the favourite was still in the race. The bookmaker needs a mechanism to adjust for the fact that the market has changed since you placed your bet. That mechanism is Rule 4.

Formally known as Tattersalls Rule 4(c), it is a deduction applied to the winnings on fixed-odds bets when one or more runners are withdrawn after the market has formed. The deduction is expressed as a number of pence per pound of winnings, and the amount depends on the odds of the withdrawn horse at the time of its withdrawal. The shorter the price of the non-runner, the larger the deduction — because the removal of a strong favourite changes the market more dramatically than the withdrawal of a 33/1 outsider. The price adjusts — and understanding how, and by how much, is essential for anyone who bets regularly on UK horse racing.

The Tattersalls Rule 4 Deduction Scale

The Rule 4 deduction scale is set by the racing authority and applies uniformly across all UK bookmakers. The deduction is based on the odds of the withdrawn horse at the time it was removed from the race, and it is applied to the winnings portion of your bet — not to the stake. The full scale runs as follows.

If the withdrawn horse was priced at 1/9 or shorter, the deduction is 90p in the pound — meaning 90% of your winnings are taken. At 2/11 to 2/9, the deduction is 80p. At 1/4 to 2/7, it is 70p. At 3/10 to 2/5, 65p. At 4/9 to 8/15, 55p. At 8/13 to 4/5, 50p. At 5/6 to evens, 45p. At 21/20 to 6/4, 40p. At 13/8 to 7/4, 35p. At 15/8 to 9/4, 30p. At 5/2 to 3/1, 25p. At 10/3 to 4/1, 20p. At 9/2 to 11/2, 15p. At 6/1 to 9/1, 10p. At 10/1 to 14/1, the deduction is 5p in the pound. Anything withdrawn at 14/1 or longer carries no deduction at all.

These deductions apply across a market where the Gambling Commission’s latest data shows online horse racing generating £766.7 million in gross gambling yield annually. Rule 4 is not an obscure technicality — it is a daily reality in a market of that scale, applied every time a horse is withdrawn between the early-morning declarations and the start of a race.

When more than one horse is withdrawn from the same race, the deductions are cumulative up to a maximum total of 90p in the pound. So if a 4/1 shot (20p deduction) and a 7/1 shot (10p deduction) are both withdrawn, the total Rule 4 deduction on your bet is 30p in the pound. In extreme cases — multiple withdrawals in a small field — the cumulative deduction can become substantial, and your winnings may be significantly less than the fixed odds you originally took.

What Rule 4 Means for Your Actual Returns

The theory is one thing; the impact on your actual returns is another. Consider a concrete example. You place £10 on a horse at 5/1 in a race where the 2/1 favourite is subsequently withdrawn. The Rule 4 deduction for a withdrawal at 2/1 is 30p in the pound. Your horse wins. Without Rule 4, your return would be £60 (£50 profit plus your £10 stake). With the 30p deduction, 30% of your profit is removed: £50 x 0.30 = £15 deducted. Your actual return is £45 (£35 profit plus your £10 stake). That is a £15 reduction from what you expected to win.

The sting is sharper when the withdrawn horse was a short-priced favourite. If an odds-on favourite at 4/6 is withdrawn, the deduction is 50p — half your winnings disappear. On a £10 bet at 5/1, that is £25 removed from your expected profit, leaving you with just £35 instead of £60. In races where two short-priced horses are withdrawn, cumulative deductions can eat into your returns so aggressively that a winning bet feels like a loss.

Rule 4 also applies to each-way bets, affecting both the win and place parts independently. If your horse wins and the Rule 4 deduction is 25p, you lose 25p per pound on both the win return and the place return. On an accumulator, Rule 4 deductions are applied to the individual leg where the withdrawal occurred, and the adjusted return from that leg then carries forward into the subsequent legs. This means a Rule 4 deduction in the first leg of a four-fold reduces the compounding base for the entire accumulator.

Cash-out values are also affected. If a bookmaker offers you a cash-out price on a bet that has been subject to Rule 4, the cash-out calculation will already factor in the deduction. You may notice the cash-out offer is lower than you expected — that is Rule 4 working in the background, adjusting the value of your position to reflect the reduced field.

How to Minimise Rule 4 Exposure

You cannot avoid Rule 4 entirely if you bet at fixed odds with bookmakers, but you can minimise your exposure. The most straightforward approach is to place your bets closer to the off time. Most withdrawals happen in the morning or early afternoon, when trainers make final decisions based on the going, the horse’s wellbeing, or tactical considerations. By waiting until closer to the start — the final 15 to 30 minutes — you reduce the window in which a withdrawal can occur between your bet and the race. The trade-off is that prices may shorten in that window as the market matures, so you might sacrifice a few points of value for the certainty of betting into a confirmed field.

Best Odds Guaranteed offers a partial hedge against Rule 4 in certain scenarios. If a non-runner causes the SP of your selection to drift higher (because the withdrawn horse was a rival), BOG will pay you at the higher SP. The Rule 4 deduction still applies to your original fixed-odds bet, but the SP bump from BOG can offset some or all of the deduction. This is a situational benefit rather than a systematic protection, but it is worth being aware of when you are weighing up whether to take an early price or wait.

Betting exchanges offer the cleanest escape from Rule 4. On Betfair Exchange, there are no Rule 4 deductions — period. If a horse is withdrawn, the market adjusts in real time as other punters react to the news, and the prices on the remaining runners contract naturally. You are never subject to a post-facto deduction on a matched bet. The trade-off is that exchange bets carry commission on net winnings — Betfair’s base rate rose to 6% for UK horse racing in June 2025, according to Racing Post reporting — but for punters who regularly face Rule 4 deductions on sportsbook bets, the exchange’s absence of deductions can represent a net saving.