How is a Rule 4 deduction calculated?
Rule 4 normally reduces the profit from a winning fixed-price bet after a relevant non-runner is withdrawn. The returned stake is kept separate. Multiply the original profit by the deduction rate, subtract that amount from the profit, then add the stake back.
| Step | Calculation |
|---|---|
| Original profit | Stake × fractional odds |
| Deduction | Original profit × deduction pence ÷ 100 |
| Adjusted return | Stake + original profit − deduction |
Worked example: £10 at 4/1 with a 20p deduction
A £10 win bet at 4/1 makes £40 profit before the deduction. Rule 4 removes 20% of that profit, which is £8. The adjusted return is therefore £42: the £10 returned stake plus £32 adjusted profit.
| Stake | Price | Original profit | Deduction | Adjusted return |
|---|---|---|---|---|
| £10.00 | 4/1 | £40.00 | £8.00 | £42.00 |
Standard Rule 4 deduction table
The deduction is linked to the withdrawn horse's price at the relevant time. A shorter-priced non-runner has a larger effect on the remaining market, so it produces a larger standard deduction.
| Price of withdrawn horse | Deduction per £1 profit |
|---|---|
| 1/9 or shorter | 90p |
| 2/11 to 2/17 | 85p |
| 1/4 to 1/5 | 80p |
| 3/10 to 2/7 | 75p |
| 2/5 to 1/3 | 70p |
| 8/15 to 4/9 | 65p |
| 8/13 to 4/7 | 60p |
| 4/5 to 4/6 | 55p |
| 20/21 to 5/6 | 50p |
| Evens to 6/5 | 45p |
| 5/4 to 6/4 | 40p |
| 8/5 to 7/4 | 35p |
| 9/5 to 9/4 | 30p |
| 12/5 to 3/1 | 25p |
| 16/5 to 4/1 | 20p |
| 9/2 to 11/2 | 15p |
| 6/1 to 9/1 | 10p |
| 10/1 to 14/1 | 5p |
| Over 14/1 | No deduction |
When Rule 4 may not apply in the same way
Ante-post bets commonly use all-in, run-or-not terms. Bets placed after a market has been reformed already use prices formed without the earlier withdrawal. Each-way bets have separate win and place profit calculations, and operator-specific concessions can change the final deduction.
For an each-way bet, first use the each-way calculator to separate the two returns. Then check the operator's published rule and the deduction shown on the settled bet. The calculator reproduces the arithmetic; it cannot decide whether a bookmaker applied its terms correctly.