What are Rule 4 deductions?

‘Rule 4’ is a general, industry-standard rule of betting, which allows bookmakers to legitimately make deductions from winning bets in the event that one or more horses are withdrawn from the race in question. If you place a win or each-way bet and take an early or board price, the odds you receive obviously reflect the chance, in the eyes of the bookmaker, your selection holds against the other horses in the race at the time you place the bet. If one of the other horses is withdrawn, the chances of your selection increase, so to prevent you having an unfair advantage, the bookmaker makes a so-called ‘Rule 4 deduction’ from your winnings, consummate with the price of the withdrawn horse at the time of withdrawal.

If a withdrawn horse was offered at odds longer than 14/1, no Rule 4 deduction is made. Thereafter, deductions are made at all rates from £0.05 in £1.00 for horses offered at odds between 10/1 and 14/1 right up to £0.90 in £1.00 for horses offered at prohibitive odds of 1/9 or shorter. Obviously, horses may be withdrawn at differing times, possibly leading to two, three or more Rule 4 deductions, depending on their respective odds. However, the maximum cumulative deduction on any race is £0.90 in £1.00.