Rule 4 deductions reduce the winnings on an affected horse-racing bet after another runner is withdrawn. For an ordinary winning cash single, the deduction applies to profit, not the stake returned with it. A deduction of 20p in the pound means £20 comes off £100 of winnings. The price used to select that deduction belongs to the withdrawn horse, not the horse you backed.
This guide is for readers checking a bookmaker's settlement. It uses Betfair Sportsbook and William Hill's British-facing published rules, reviewed on 15 October 2026. Those examples do not establish the terms of every country, operator or racing product. No customer account or payout was tested.
What Rule 4 changes
A withdrawal changes the field against which earlier prices were offered. Bookmakers can form a new market for subsequent bets; an earlier winning ticket may instead have a deduction applied under its terms. The Tattersalls Committee explains the on-course background of its betting rules. For an online ticket, read the bookmaker's actual product rules rather than treating the name Rule 4 as a worldwide statutory formula.
Two outcomes need separating. If the horse you backed becomes a qualifying non-runner, the question is whether that selection is void and its stake refunded. If a different horse withdraws and yours wins, the question is whether your winnings attract a deduction. Betfair's Sportsbook horse-racing rules distinguish those cases and make exceptions for Future Racing. Our settlement guide covers the wider ticket-to-account process.
A worked Rule 4 calculation
Consider a fictional £20 cash win single at 5/1, equivalent to decimal odds of 6.00. Assume your horse wins outright. Another horse was priced at 4/1 when withdrawn after your bet was accepted, and the applicable win-market deduction is 20p in the pound. That 4/1 price falls within Betfair's published 20p band. The stake, accepted odds and result below are teaching inputs, not an actual race or account statement.
| Step | Calculation | Amount |
|---|---|---|
| Stake | Cash committed to the single | £20.00 |
| Original profit | £20 × 5 | £100.00 |
| Deduction | £100 × 20% | £20.00 |
| Adjusted profit | £100 minus £20 | £80.00 |
| Total return | £80 profit plus £20 stake | £100.00 |
The formula is: total return = stake + original profit × (1 minus the deduction rate). It assumes no other settlement adjustment, promotion or charge. Our odds guide explains why 5/1 represents profit of five times the stake, whereas decimal 6.00 includes the returned stake.
Applying 20% to the original £120 gross return would deduct £24 and leave £96. That is not this calculation: it would also reduce the stake component. Equally, applying the deduction directly to decimal 6.00 would produce the wrong adjusted price. For this example, the return-equivalent decimal price is 1 + (6.00 minus 1) × 0.80 = 5.00.
The £100 return is not a £100 gain. It contains the £20 you committed, leaving £80 profit. Nor does this arithmetic establish what could be withdrawn from an account containing other bets or transactions.
Find the withdrawn runner's price and the right market
Betfair's non-runner help uses the last Betfair price available when the relevant horse is withdrawn to determine Rule 4 on a price-taken bet. That need not be the price you saw earlier or another bookmaker's quote. Save the withdrawal time, runner identity and price used, then match them to the relevant table.
Do not apply the ordinary win table to every product. Betfair publishes a separate place-only deduction table whose entries depend on the non-runner's place price and the number of places paid. Its stated cumulative cap there is 95p in the pound, compared with 90p in its ordinary non-runner win provisions. An each-way ticket also needs its accepted win and place terms checked; the worked example above is a win single only.
Timing, starting price and further withdrawals
A bet accepted in a reformed market should be examined against that market's subsequent withdrawal history. It is not enough to read the final list of non-runners and apply every deduction to every ticket. Betfair's rules address further withdrawals after a market has been reformed.
Starting price, or SP, is not an unconditional exemption. The same rulebook allows an SP deduction where there was insufficient time to form a new market. Check the actual price basis on the accepted ticket and the operator's explanation of a late withdrawal.
William Hill's Rule 4 explanation specifies a 90p total cap for multiple withdrawals and says it waives a deduction when the market's total is 5p in the pound. That is a named operator's concession, not a promise that every bookmaker waives each 5p component. Ask for the applicable combined deduction and how each withdrawal was treated rather than assuming every percentage should simply be applied again to the same return.
Ante-post and exchange bets need separate rules
Do not assume an ante-post non-runner receives the day-of-race refund. Betfair's Future Racing section generally accepts bets on a run-or-not basis and lists exceptions, including specified ballot or elimination circumstances. William Hill's help page likewise distinguishes ante-post treatment. A separately advertised concession must be checked on the actual accepted bet; the calendar date alone does not identify every contractual condition.
An exchange is another distinct product. Betfair's Rule 4 help describes a non-runner reduction factor applied to matched exchange prices, affecting backers and layers. Do not substitute the sportsbook profit-deduction example for an exchange price adjustment. Ordinary exchange commission is a further calculation on the settled market result, not another name for the withdrawal adjustment.
Check an unexpected Rule 4 deduction
- Save the accepted ticket: selection, race, bet type, stake, odds, acceptance time and any special terms.
- Identify which runner was withdrawn and when. Separate your own non-runner from a withdrawal affecting another selection's winnings.
- Ask which withdrawal price and deduction table were used. Record the product, market and any reformed-market timing.
- Reproduce the profit calculation before adding the returned cash stake. Keep each-way parts or multiple-bet components separate where their rules require it.
- Request the combined deduction and any applicable waiver. Check whether another entry reflects a void, dead heat, promotion, commission or correction.
- Compare the calculation with the settled ticket and account entries. If they differ, ask the operator for the governing clause and a breakdown, retaining its reply.
Rule 4 deductions are easier to check when the stake, profit, withdrawal price and market timeline are distinct records. A winning status does not mean the original displayed return survived every applicable condition. This guide explains settlement, not a method for making betting profitable. Gambling can lose money and is restricted to adults where lawful.
Frequently asked questions
Does Rule 4 take money from my stake?
For the ordinary winning cash-single calculation described here, the deduction reduces winnings before the stake is added back. William Hill's published explanation expressly distinguishes those amounts. A free bet, each-way ticket, exchange position or other special product may need a different calculation; identify the bet before applying the formula.
Which horse's odds determine the deduction?
The relevant price is the withdrawn runner's price under the bookmaker's rules, not the accepted odds of your winning selection. Betfair specifies its last available price at withdrawal for price-taken bets. The market type and any later reformation still matter, so a different bookmaker's historical quote is not enough.