What is Rule 4 in Horse Racing?

rule 4 horse racing

What is Rule 4?

Rule 4 is a deduction made on horse racing bet when a horse is withdrawn from a race.

If a horse is withdrawn from a race, the remaining horses stand a better chance of winning. Therefore, their odds are reduced to reflect their new chances.

Rule 4 deductions can come as a bit of a shock to punters who don’t usually bet on horses and panic may set in when you realise your returns are nowhere near what you expected them to be.

Let’s say that you backed the 2nd favourite in a race at odds of 4/1 with the favourite being odds-on at 4/6. The favourite then withdraws from the race which means your horse is now the new favourite but you backed it at 4/1 which doesn’t reflect it’s new chances of winning. The odds on your horse should now be much lower and will be changed despite you placing the bet at 4/1 prior to knowing the favourite would withdraw.

Seem unfair? Well, in a way it is but it makes sense. Everyone who backed the original favourite will have their stake refunded by the online bookmakers and so it’s only fair that the odds on your horse are now changed to reflect the current market.

How Rule 4 deductions are calculated

Rule 4 deductions are calculated based on the odds of the withdrawn horse and so it should be pretty simple to work out your expected return should your horse win.

It’s important to remember that the Rule 4 deduction is applied to your winnings and not to your returned stake. The deduction percentage is shown alongside the odds of the withdrawn horse. You can also view the percentage deduction as pence per pound. For example a 50% deduction is the same as £0.50 deducted from every £1 of winnings.

Odds of withdrawn horse Deduction %
1/9 or shorter 90%
2/11 to 2/17 85%
1/4 to 1/5 80%
3/10 to 2/7 75%
2/5 to 1/3 70%
8/15 to 4/9 65%
8/13 to 4/7 60%
4/5 to 4/6 55%
20/21 to 5/6 50%
Evens (1/1) to 6/5 45%
5/4 to 6/4 40%
13/8 to 7/4 35%
15/8 to 9/4 30%
5/2 to 3/1 25%
10/3 to 4/1 20%
9/2 to 11/2 15%
6/1 to 9/1 10%
10/1 to 14/1 5%
Over 14/1 No Deduction

Matched betting when there’s a Rule 4 deduction

It’s common to panic if there is a Rule 4 deduction and you have not only backed a horse but also layed it. What will happen? Will you lose money if your horse wins as the payout will be less?

Thankfully, the answer is no.

Betting exchanges also apply Rule 4 deductions and so your lay bet odds should also be reduced. However, your expected qualifying loss may be slightly different than expected. It could be higher or lower although it shouldn’t be a huge change. If you’re using a free bet and there is a Rule 4 deduction, it could have an effect on your expected profit. You generally make the most profit by using your free bets on bets with odds of 5.0 or greater. However, if your odds are dramatically reduced, it’s possible that your profits will be also.

You shouldn’t have to do anything if there is a Rule 4 deduction as both the bookmaker and betting exchange should make the changes to the odds and your return automatically. However, you may have to edit your spreadsheet or profit tracker if you use one to record your profits/losses based on the new odds.

Calculating the back odds after a Rule 4 deduction

You may need to calculate the back odds after a Rule 4 deduction has been applied. You may need to do this if you haven’t layed your bet yet. To do so, you can use the formula below:

( back odds – 1 ) x ( 1 – Rule 4 deduction ) + 1

For example, if you backed a horse at 5.0 and the Rule 4 deduction was £0.50, the new odds would be:

(5 – 1) x (1 – 0.5) + 1 = 3.0

By robertc


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