Rule 4 Deductions, Explained

You back a horse at 7/2 (4.50) in the morning. It wins in the afternoon. The return lands in your account and it is smaller than you expected — not by pennies, by pounds. Nothing has gone wrong. A horse was withdrawn from the race after you struck your bet, and what you have just met is a Rule 4 deduction.

Rule 4 is one of the least understood pieces of everyday betting mechanics, mostly because nobody explains it until it has already happened to you. It is not a bookmaker trick, and it is not discretionary. It is an industry-wide rule with a fixed, published scale, and once you understand the logic behind it, the numbers stop feeling arbitrary.

This is the whole thing, properly: what the rule is, why it exists, exactly when it bites, the full deduction table, and the parts that catch people out — each-way bets, accumulators, and the different way exchanges handle a non-runner.

Why Rule 4 exists

Every price you take is a price for the race as it stood at that moment. If a 12-runner handicap loses its second favourite an hour before the off, the race has changed. Every remaining horse now has a better chance of winning than it did when you placed your bet. Your 7/2 shot is no longer a true 7/2 shot — with a live danger removed, it might be a 5/2 shot in the new market.

Left uncorrected, that would be a one-way problem. Bookmakers would be paying out at prices that no longer reflected the race being run, and their answer would be simple: stop offering early prices at all, or void every bet whenever a horse comes out. Neither would suit punters. So the industry settled on a compromise, written into the Tattersalls Committee Rules on Betting — the long-standing framework governing betting disputes in Britain — under Rule 4(c). The bet stands, at the price you took, but the winnings are trimmed by a fixed amount that reflects how big a player the withdrawn horse was.

That last part matters. The deduction is not one-size-fits-all. It is scaled to the price of the horse that came out. Lose a 1/2 favourite and the whole shape of the race changes, so the deduction is heavy. Lose a 12/1 outsider and the effect is marginal, so the deduction is 5p in the pound — and if the withdrawn horse was bigger than 14/1, there is no deduction at all.

When it applies — and when it doesn't

Rule 4 applies to bets struck before the withdrawal, at whatever price was available at the time — an early price, a board price on course, or a price taken online that morning. The logic is the timeline: your price was set in a market that included the withdrawn horse, so your price gets adjusted.

Once a horse is officially declared a non-runner, the bookmakers reform the market. New prices go up that already account for the smaller field. Bets struck at those new prices carry no deduction for that withdrawal — the correction is baked into the price you took. This is the answer to a question that confuses a lot of people: a withdrawal does not punish everyone, only those who bet before it happened.

Starting Price bets are usually safe, for the same reason. The SP is returned at the off, from a market that already knows who is running. The exception is a very late withdrawal — a horse that whips round at the start and is taken out under starter's orders, say — where there is no time to form a fresh market. In that case Rule 4 can apply to SP bets too. If the difference between taking a price and taking SP is fuzzy, our guide to SP, board prices and BSP walks through it.

Two more edges worth knowing. If more than one horse is withdrawn, the deductions are added together, but the total can never exceed 90p in the pound — you always keep at least 10p of every pound of winnings, plus your stake. And when the scale calls for only a 5p deduction, some firms waive it entirely as a concession. That varies by bookmaker, and it is always in your favour when it happens.

The full deduction scale

The scale below is the industry-standard Tattersalls scale as published at the time of writing (August 2026), cross-checked against multiple independent sources. The price that matters is the withdrawn horse's price at the time it was taken out — not its morning price, and not what you fancied it should have been.

Read it as pence in the pound, off winnings. A 25p Rule 4 means every £1 you would have won becomes 75p. Your stake is never touched.

Rule 4 comes off your winnings, never your stake. If you remember one thing from this page, make it that — and before you assume you have been short-changed, check the price of the horse that came out.

The arithmetic, worked through

Example one: a win single. You have £10 on a horse at 7/2 (4.50). Before the race, a rival priced at 3/1 is withdrawn. From the table, 3/1 sits in the 12/5–3/1 band: a 25p deduction.

Your horse wins. Without a non-runner, the return would have been £45 — £35 winnings plus your £10 stake. Instead:

• Winnings at 7/2: £10 × 3.5 = £35.00
• Deduction: £35.00 × 0.25 = £8.75
• Winnings after Rule 4: £35.00 − £8.75 = £26.25
• Total return: £26.25 + £10 stake = £36.25

You have effectively been paid at around 21/8 (3.63) rather than 7/2. That is the honest way to think about a Rule 4: it converts the price you took into the price the race deserved once the field changed.

Example two: a heavier deduction. You have £20 on a horse at 2/1 (3.00) and the 4/6 favourite is pulled out at the start. From the table, 4/6 sits in the 4/5–4/6 band: a 55p deduction.

• Winnings at 2/1: £20 × 2 = £40.00
• Deduction: £40.00 × 0.55 = £22.00
• Winnings after Rule 4: £40.00 − £22.00 = £18.00
• Total return: £18.00 + £20 stake = £38.00

A £60 return becomes £38. It stings, but consider what actually happened: you backed a horse to beat a field that included an odds-on favourite, and it never had to. The 2/1 you took was priced for a much harder job.

Each-way bets and accumulators

An each-way bet is two bets, and Rule 4 applies to both halves — the win part and the place part are each deducted at the same rate.

Say you have £5 each-way on a 10/1 (11.00) shot, at one-fifth the odds for a place, and a 6/4 chance is withdrawn: a 40p deduction. Your horse wins.

• Win part: £5 × 10 = £50 winnings; less 40p in the pound = £30.00; plus £5 stake = £35.00
• Place part: place odds are 10/1 ÷ 5 = 2/1; £5 × 2 = £10 winnings; less 40p = £6.00; plus £5 stake = £11.00
• Total return: £46.00, against £70.00 with no deduction

One thing Rule 4 does not do on a standard each-way bet: it does not change the place terms. Whether a withdrawal shrinks the field enough to move a race from paying four places to three is a separate matter, governed by field size, and it can hurt more than the deduction itself. That interaction is covered properly in our guide to each-way value.

In an accumulator, Rule 4 applies leg by leg. A deduction in one race trims the winnings from that leg only — but because each leg's return rolls into the next, the effect compounds through the bet. Take a £10 double: 2/1 (3.00) in the first leg, 5/1 (6.00) in the second, where a 9/2 shot comes out of the second race — a 15p deduction.

• Leg one wins clean: £10 × 3.00 = £30.00 rolls forward
• Leg two: winnings of £30 × 5 = £150, less 15p in the pound = £127.50, plus the £30 rolling stake = £157.50
• Without the deduction the double returns £180.00

Exchanges handle it differently

Betfair's Exchange does not use Rule 4 at all in its win markets. It uses reduction factors. Every horse in a market is assigned a reduction factor reflecting its share of the market, and when a horse is withdrawn, the prices of already-matched bets are reduced by that percentage — applied to the whole price, not just the winnings, and applied to backers and layers alike. That last part is the point: on an exchange, the layer of your bet is another customer, and they need protecting from a suddenly easier race just as bookmakers do.

Two practical differences follow. First, because the reduction applies to the matched price rather than the winnings, the arithmetic is not the same as a Tattersalls deduction, even when the percentages look similar. Second, Betfair does not apply reductions at all when the withdrawn horse's reduction factor is under 2.5% — the equivalent of the fixed-odds world ignoring big outsiders. Unmatched bets in the win market are cancelled when a horse is withdrawn, so anything you resubmit is priced against the new race.

The Betfair Sportsbook — the fixed-odds side — follows conventional Rule 4, like any other bookmaker. It is only the Exchange that runs on reduction factors.

Keeping it in perspective

Rule 4 is not a leak you can plug, and it is not a con. It is the market correcting itself after the race changed, using a scale that has been public for decades. Deductions are part of the price of taking early prices — the same habit that sometimes gets you 7/2 about a horse that goes off at 2/1 will sometimes get you a 25p deduction when the favourite is scratched at breakfast. Over time, one comes with the other, and neither changes the basic truth that most punters lose more than they win. Nothing on this page alters that; it just means that when a return looks light, you will know exactly why, and be able to check the sum yourself.

What you can do is be aware. Non-runners cluster in predictable places — going changes overnight, small fields on soft ground, doubtful runners flagged in the morning trade. If a horse you fancy is priced short and its main market rival is a doubtful runner, taking an early price carries a live Rule 4 risk that the price itself never advertises. Understanding that is the same discipline as reading the overround: knowing what a price actually pays, not what it appears to pay.

Keep the table handy. The next time a return arrives short, find the non-runner, find its price at withdrawal, find the band. The sum will check out — it always does. The rest of the Academy is built the same way: one mechanism at a time, explained properly.