The Rule 4 logic is relatively straightforward to understand. Whether you're new to horse racing (where this term is most commonly used) or a seasoned horse racing punter, Rule 4 can be frustrating, but it's a necessary evil and makes sense.
Rule 4 originates from Tattersalls Rule of Racing which governs horse racing and is calculated based on the price of the withdrawn horse. It makes good sense, if the hot favourite is withdrawn and you've bet on the 2nd favourite, then the chances of you horse winning will increase significantly. Rule 4 is there to adjust your winnings that will be more representative of your chances of winning.
When does rule 4 come into effect?
A Rule 4 deduction is applied to your winnings that bookmakers apply when a non-runner is declared in a race or event that you've already placed a bet on. The best way it can be described is a way for bookmakers to manage their liability when there are non-runners / withdrawals in a horse race (or multi entrant competition, such as golf).
Imagine you've backed the second favourite in a horse race at 2/1, but the favourite withdraws from the race 30 minutes before the race begins. The favourite was priced at evens (2.00). Your horse has a greatly increased chance of winning now that the main competitor is no longer competing. A Rule 4 will be applied to represent this change, so should your horse win, you'll win a smaller percentage of your expected winnings.
How is a Rule 4 deduction applied?
Because of your decisive edge they even the playing field and the system is quite simple. The size of the deduction you face is determined by the odds of the horse that dropped out.
| Decimal Odds | Fractional Odds | Rule 4 Deduction |
|---|---|---|
| 1.11 or lower | 1/9 or lower | 90p |
| 1.12 to 1.18 | 2/17 to 2/11 | 85p |
| 1.20 to 1.25 | 1/5 to 1/4 | 80p |
| 1.29 to 1.32 | 2/7 to 3/10 | 75p |
| 1.33 to 1.40 | 1/3 to 2/5 | 70p |
| 1.44 to 1.53 | 4/9 to 8/15 | 65p |
| 1.55 to 1.63 | 4/7 to 8/13 | 60p |
| 1.66 to 1.80 | 4/6 to 4/5 | 55p |
| 1.83 to 1.95 | 5/6 tp 20/21 | 50p |
| 2.00 to 2.20 | Evens to 6/5 | 45p |
| 2.25 to 2.50 | 5/4 to 6/4 | 40p |
| 2.60 to 2.75 | 13/8 to 7/4 | 35p |
| 2.80 to 3.25 | 15/8 to 9/4 | 30p |
| 3.40 to 4.00 | 5/2 to 3/1 | 25p |
| 4.20 to 5.00 | 10/3 to 4/1 | 20p |
| 5.50 to 6.50 | 9/2 to 11/2 | 15p |
| 7.00 to 10.00 | 6/1 to 9/1 | 10p |
| 11.00 to 15.00 | 10/1 to 14/1 | 5p |
| Over 15.00 | Over 14/1 | No Deduction |
The reduction can never be more than 90% (90p per £1.00 of profit), and the reduction increases the shorter the price of the withdrawn horse.
Any horses that withdraw priced over 14/1 (15.00) will see no deduction applied to other horses (as their absence is unlikely to change the outcome of the race).
Using the previous example, your 2/1 second favourite will see a 45p reduction in winnings due to the fact the withdrawn horse was priced at evens (2.00). That's a 45p reduction for every £1 of profit you were expecting to win prior to the withdrawal.
Good tipsters will keep track of rule 4 deductions
Rule 4 deductions are almost exclusive to horse racing, but also appears in multi entrant events such as golf. It's a frustrating, but necessary evil. Rule 4 (Deductions) is, on paper, a term that everyone should be using. Any good and fair tipster will be honest about including Rule 4 deductions in their betting results spreadsheets, although some more casual tipsters may think it's not important, and those more interested in just appearing as profitable as possible to entice membership sign-ups may ignore it all together.
A professional bettor and a truly good, honest tipster will be more interested in knowing exactly what they stand whilst also providing transparency and are more likely to embrace and use the term when documenting or discussing their betting activity.
Make sure if you follow any tipster, that they include R4 deductions in their results, otherwise you'll see a big differential between their results, and the profits you're able to obtain.
If you're feeling comfortable with terminology, it might be the right time to learn about the different bet types and how to use them to your advantage.