Rule 4 Deductions Explained

You take 5/1 about a horse in the morning. By lunchtime the 3/1 favourite has been pulled out. Your horse bolts up, you open the app expecting £60 back from a £10 bet, and the return says £47.50. Nobody has made a mistake. That's Rule 4, and it's one of the most misunderstood lines in British horse racing betting.

The good news is that it runs on a fixed scale. Learn the deduction table and the simple maths behind it and you can work out any Rule 4 deduction in seconds. You'll also know exactly why it happened.

It doesn't treat every bet the same way, though. Each-way bets, Best Odds Guaranteed, ante-post punts and races with two or more non-runners all have their own quirks, so we'll take them one at a time with real numbers, then finish with the angles that stop it catching you out.

Rule 4 is a deduction from your winnings when a horse is withdrawn from a race after you've taken a price. It takes its name from Rule 4 of the Tattersalls betting rules, which go back to the 1800s, and it's expressed in pence in the pound. A 20p deduction means you lose 20p from every £1 of profit.

Your stake is never touched. If the difference between stake, profit and total return is a bit fuzzy, our guide to what "stake not returned" means sorts it out, and you'll find the Rule 4 sums much easier with that clear in your head.

Why Rule 4 exists

Take a horse out of a race and every runner left in it has a better chance of winning. The price you took was set for a bigger, stronger field, so it's now too generous. Rule 4 trims your winnings back towards what the price would have been if the withdrawn horse had never been in the market.

When Rule 4 applies

The window is narrow. Rule 4 only applies to withdrawals after final declarations and before the horse comes under starter's orders. Final declarations are usually made 24 hours before the race, sometimes 48. A horse that's never declared doesn't trigger it, and once the field is under orders the window has shut.

Here's the part that trips people up. The deduction depends on the price of the withdrawn horse, not the one you backed. A short-priced favourite coming out costs you far more than a 12/1 outsider, because the race looks very different without the favourite in it.

Rule 4 is driven by the horse that pulled out, not the one you backed.

Deductions run from 5p to 90p in the pound. Find the band the withdrawn horse's price falls into and you have your deduction. These are the industry-standard Tattersalls Rule 4(c) deductions, based on the withdrawn horse's price in the market you bet into.

Odds-on non-runners bring the heaviest cuts. The scale keeps climbing in 5p steps from 45p at evens, so a 1/4 shot means a 70p deduction, and a horse at 1/9 or shorter takes the maximum 90p. Lose a 1/9 shot from the field and you keep just 10p of every pound of profit.

At the other end, anything withdrawn at bigger than 14/1 costs you nothing. A couple of rags coming out of a big handicap field is nothing to worry about.

Every Rule 4 sum is the same three steps. Work out the profit at your price, take the deduction off that profit, then add your stake back.

Profit         = stake x fractional odds
Deduction      = profit x (pence / 100)
Return         = stake + profit - deduction

A £20 win bet with a 4/1 non-runner

This one comes straight from William Hill's help pages. You back a horse for £20 at 7/4 and a 4/1 shot is withdrawn, which means a 20p deduction.

Profit at 7/4      = £20 x 7/4   = £35.00
Deduction (20p)    = £35 x 0.20  = £7.00
Adjusted profit    = £35 - £7    = £28.00
Return             = £20 + £28   = £48.00   (instead of £55.00)

A £10 bet with an evens non-runner

Paddy Power's example shows how hard a short-priced withdrawal bites. £10 at 11/4, and the evens favourite comes out: 45p in the pound.

Profit at 11/4     = £10 x 11/4    = £27.50
Deduction (45p)    = £27.50 x 0.45 = £12.37 (rounded)
Adjusted profit    = £15.13
Return             = £10 + £15.13  = £25.13   (instead of £37.50)

That's more than £12 gone because of a horse you never backed.

A £10 bet with a 7/1 non-runner

A much gentler cut. £10 at 4/1, and a 7/1 runner is withdrawn, which sits in the 10p band.

Profit at 4/1      = £10 x 4     = £40.00
Deduction (10p)    = £40 x 0.10  = £4.00
Adjusted profit    = £40 - £4    = £36.00
Return             = £10 + £36   = £46.00   (instead of £50.00)

Rule 4 in decimal odds

If you think in decimals, one line gives you your effective price after the deduction:

New decimal price = (decimal odds - 1) x (1 - deduction) + 1

Example: 6.00 (5/1) with a 20p deduction
         (6.00 - 1) x 0.80 + 1 = 5.00   (effectively 4/1)

Rule 4 cuts both halves of an each-way bet at the same pence-in-the-pound rate, and again it's only the winnings that suffer. If each-way terms are new to you, our complete guide to each-way betting covers place terms and fractions properly.

Say you have £5 each-way (£10 total) at 10/1, quarter-odds on three places, and a 20p Rule 4 comes in.

Win part:   profit £5 x 10/1       = £50.00
            20p deduction          = £10.00
            return £5 + £40        = £45.00

Place part: profit £5 x (10/1 / 4) = £12.50
            20p deduction          = £2.50
            return £5 + £10        = £15.00

Horse wins:        £45 + £15 = £60.00   (instead of £72.50)
Horse places only: £15.00               (instead of £17.50)

The place part already pays at a fraction of the odds, so a heavy deduction leaves it looking thin. When a big Rule 4 is on the cards, an each-way bet at a short-ish price can return barely more than your stake for a placing. We'd weigh that up before splitting the stake, and on a short price we'd often rather go win-only.

When two or more horses come out, the deductions are added together. The total can never go above 90p in the pound, which is a cap you'll be glad of on a messy day.

Evens (45p) + 6/4 (40p)  = 85p    -> 85p applies
1/4 (70p)   + Evens (45p) = 115p  -> capped at 90p

£10 at 5/1 with the 90p cap:
Profit kept = £50 x 0.10 = £5.00
Return      = £10 + £5   = £15.00   (instead of £60.00)

Re-formed markets

After a withdrawal, the bookmaker usually forms a new market with fresh prices. So the time you struck your bet matters as much as which horse came out. Sky Bet uses this example: Horse B (7/4) is withdrawn at 10am and the market re-forms, then Horse C comes out too. C was 6/1 in the original market and 5/2 in the new one. The market re-forms again at 3pm.

Put £10 at 5/1 on that race before 10am and you take the full 45p. Your £50 of profit becomes £27.50, and the return is £37.50.

Small deductions and multiples

Some bookmakers, William Hill among them, waive a Rule 4 when the total deduction on the market is just 5p. Bookmakers can also choose to waive small deductions in high-profile races, but that's their call, not something you're entitled to. In accumulators and other multiples, including Lucky 15, Yankee and other full-cover bets, the deduction only hits the leg in the race with the withdrawn horse. The rest of your bet settles as normal.

Best Odds Guaranteed (BOG) pays you at whichever is bigger: the price you took or the starting price. Rule 4 muddies that, because the deduction cuts the winnings at your taken price.

Sky Bet's rule shows how it can work. If you take a price that then gets hit by Rule 4, the deduction stands unless your horse returns at a bigger SP. In that case you're paid at SP with no Rule 4, unless the SP itself carries a deduction. Other bookmakers handle this differently, so read the BOG terms of whoever you bet with. Two minutes with the small print can be worth real money.

SP bets and the late withdrawal

Bets struck at starting price are usually unaffected, because the SP is formed in a market that already knows about the non-runner. The exception is a very late withdrawal with no time to form a new market. Then the deduction can apply to every bet, SP included.

Dead heats

Rule 4 itself never touches your stake, whatever the size of the deduction. If your horse dead-heats, the dead-heat rules kick in alongside Rule 4, so expect to see both in the settlement.

Rule 4 does not apply to ante-post bets, the ones placed before final declarations. That's part of the deal you strike for the bigger prices available weeks or months out. The catch is obvious enough: if your horse doesn't run, you generally lose your stake.

So keep an eye out for non-runner no bet and non-runner money back offers. When a bookmaker runs one, a horse that misses the line-up gets you your stake back, which takes most of the sting out of betting early.

Reserves and exchanges

Irish racing often has reserves, and bookmakers don't all treat a reserve's withdrawal the same way, so check your bookmaker's rules on that one. Betting exchanges don't use Rule 4 at all. They have a separate reduction-factor system, also based on the withdrawn horse's price.

A trimmed payout, not a void

Rule 4 isn't a void. Your bet stands and settles as a winner or a loser; only the winnings change. A bet that's been cancelled outright goes through a different process altogether, and our guide on why bets get voided explains what happens there.

Bookmakers show the deduction on the bet itself. Open your bet slip or My Bets and you'll see a "Rule 4 applied" note with the pence-in-the-pound figure. Run the sum yourself with the table above and it should match to the penny, give or take rounding.

Can you avoid it? No. Once a horse is withdrawn inside the window, Rule 4 applies to win and each-way bets alike, and there's no opt-out. What you do control is when you bet and how.

A quick scan of the field before you bet shows you which short-priced runners would cause the biggest deductions if they came out. Our guide to reading a horse racing racecard helps you size up a field fast, so you spot the dangers before you commit.

• Watch the withdrawn horse, not yours. The non-runner's price sets the deduction. A 16/1 shot coming out costs nothing; an odds-on favourite can take up to 90p in the pound.
• Let the market re-form. When a short-priced rival comes out, the new market prices that in. Bets struck after the re-form carry no deduction for that horse, so the fresh price can beat an early one that's been hit by Rule 4.
• Rethink each-way after a big deduction. The place part is cut at the same rate, so a heavy Rule 4 on a short-priced each-way bet leaves the placing paying very little.
• Know your bookmaker's BOG terms. With Sky Bet, a bigger SP is paid without Rule 4, which makes BOG even more valuable on days with late non-runners.
• Ante-post is a choice, not a loophole. You dodge Rule 4, but you carry the non-runner risk. Non-runner no bet offers are the sweet spot when you can find them.
• Check the settlement. The "Rule 4 applied" line on your bet slip gives you the figure. Do the sum and you'll never wonder where the money went.

Rule 4 is part of the furniture in British racing. Build it into your thinking, and keep your stakes sensible and consistent whatever the field looks like on the morning of the race.

• Ante-Post Betting & Non-Runner No Bet Explained
• Best Odds Guaranteed (BOG) Explained
• Betting Odds Explained: Fractional, Decimal and American Odds Made Simple
• Arbitrage Betting Explained: How Sure Bets Work
• Price Boosts & Enhanced Odds: Are They Actually Value?

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