What is Rule 4?
Rule 4, named after a long-standing Tattersalls betting rule, is a deduction from winnings that applies when a horse is withdrawn from a race after you have placed a fixed-odds bet.
It exists for fairness. If you back a horse at 5/1 and then a strong rival is withdrawn, every remaining runner's chance of winning has just improved. The price you took no longer reflects the real race. Rule 4 adjusts for that by taking a proportionate amount from winning bets struck at the old odds.
How the deduction is calculated
The size of the deduction depends on the odds of the withdrawn horse at the time it was pulled out. A short-priced withdrawn horse had a big share of the market, so its removal helps the others more, and the deduction is larger.
Deductions are taken as an amount per £1 of winnings (not the stake). The standard scale is approximately:
| Odds of withdrawn horse | Deduction per £1 won |
|---|---|
| Odds-on to 1/1 (evens) | 50p-55p |
| 6/5 to 2/1 | 40p-45p |
| 9/4 to 7/2 | 25p-35p |
| 4/1 to 11/2 | 15p-20p |
| 6/1 to 9/1 | 10p |
| 10/1 to 14/1 | 5p |
| Longer than 14/1 | No deduction |
A worked example
You back a horse at 4/1 with a £10 stake. Before the race a rival is withdrawn at odds of 2/1, triggering a Rule 4 of around 40p in the £1.
Your horse wins. Normal winnings would be £40. The deduction is 40p for every £1 of that £40, £16, so you receive £24 of winnings plus your £10 stake back.
Avoiding Rule 4
Because Rule 4 only applies to fixed-odds bets placed before a withdrawal, taking starting price (SP) sidesteps it entirely, the SP is calculated with the non-runner already removed.
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