Rule 4 Betting: Full Deduction Table, Formula & Examples

A withdrawal can make every remaining runner more likely to win. Fixed odds taken before the withdrawal may therefore be more generous than the revised market would offer. Rule 4 is the established adjustment used for many British horse-racing bets in that situation. The Gambling Commission describes Rule 4 as a reduction of winnings that balances the effect of a non-runner.

This guide explains the standard table, the calculation and the main matched-betting risk. It does not replace the rules attached to your bet. Operators are required to publish core settlement terms, including how they treat withdrawals and deductions, under Gambling Commission condition 4.2.6.

What Rule 4 Means

Rule 4, more precisely Tattersalls Rule 4(C), applies when a declared runner is withdrawn after a market has formed and qualifying bets were placed before the withdrawal. The standard mechanism reduces the profit on winning bets involving the runners that remain. A bet on the withdrawn horse is handled separately under the operator's non-runner rule.

The logic is market-based. Imagine a four-runner race in which the favourite is withdrawn. The other three runners now have a better chance than they had when the original prices were offered. Keeping every original price unchanged would overstate the potential return. Rule 4 adjusts those earlier bets rather than pretending the field never changed.

The Tattersalls Committee rules and deduction table remain the core reference for this calculation. Current sportsbook rules can add product-specific details, so the bet receipt and the operator's published rules remain decisive for settlement.

When Does Rule 4 Apply?

Rule 4 commonly matters when you take an early or fixed price and another horse is later declared a non-runner. The deduction is based on the price assigned to the withdrawn horse under the applicable rules, not on the price of the horse you backed.

• Your selection remains in the race: a deduction may be applied if it wins or places.
• Your selection is the non-runner: the stake is commonly refunded, subject to the non-runner and starter's-orders rules.
• The market is reformed before you bet: the new odds already reflect the smaller field, so an earlier withdrawal should not also reduce that later bet.
• The bet is ante-post: separate all-in or run-or-not terms may apply, so do not assume a refund or standard Rule 4 treatment.

The official status of a runner matters. The British Horseracing Authority non-runner rule update explains circumstances in which stewards can declare a horse a non-runner after it has been denied a fair start. A horse that simply refuses to race after coming under starter's orders may be treated differently. Check the final official declaration and the specific house rule before challenging a settlement.

The Standard Rule 4 Deduction Table

The standard table expresses the deduction as pence taken from each pound of profit. A 20p deduction means 20 percent of the profit, not 20 percent of the full return. The bands below reproduce the current core scale shown in the Tattersalls rules and current horse-racing rulebooks.

If two or more horses are withdrawn, the applicable deductions are added together. Under the current sportsbook horse-racing rules, the combined deduction does not exceed 90p per £1 of profit. The operator's published rule and settlement notice still control the exact bet.

Multiple withdrawals and a reformed market

Assume you place a £20 bet at 5.00 at 10:00. A 9/2 runner is withdrawn at 10:15, producing a 15p deduction, and the market is reformed at 10:20. A second runner priced at 6/1 is withdrawn at 10:40, producing another 10p deduction. Your 10:00 bet is exposed to both withdrawals, so the combined deduction is 25p. The original £80 profit becomes £60, and the total return is £80 after the £20 stake is added back.

A bet placed after the 10:20 reformation should be assessed against the later market and the second withdrawal only. Its own odds and timestamp matter. This is why two bets on the same eventual winner can receive different Rule 4 treatment.

How to Calculate a Rule 4 Return

For a standard fixed-odds win bet, separate the stake from the profit before applying the deduction.

1. Calculate original profit: stake x (decimal odds - 1).
2. Convert the deduction: 20p per pound becomes 0.20.
3. Calculate adjusted profit: original profit x (1 - deduction).
4. Add the returned stake: adjusted profit + original stake.

In compact form: adjusted return = stake + [stake x (decimal odds - 1) x (1 - deduction)]. You can verify the percentage step with the betting percentage calculator, but you still need the correct deduction from the bet's settlement rules.

Worked win-bet example

You stake £20 at decimal odds of 5.00. A non-runner produces a 20p deduction. The original profit is £20 x 4.00 = £80. The deduction is £80 x 0.20 = £16. Adjusted profit is £64, and the total return is £84 after the £20 stake is added back.

Rule 4 on Each-Way Bets

An each-way bet contains a win part and a place part. A non-runner can affect both the deduction and the number of places paid. This is why a standard each-way calculation made before withdrawals may no longer match the final settlement.

Start by calculating the original win and place parts separately. The each-way calculator shows the standard return before Rule 4 or revised place terms. It does not currently model non-runner deductions, so the final adjustment must follow the operator's rulebook.

Simplified each-way illustration

Assume a £10 each-way bet at decimal 6.00 with one-fifth place terms, and assume the operator applies the same 20 percent deduction to both profit parts. The win profit falls from £50 to £40. The place odds are 2.00, so the place profit falls from £10 to £8. If the horse wins, the two returned stakes plus £48 adjusted profit produce a total return of £68.

That example is deliberately labelled simplified. A withdrawal may also revise the place terms, and place-only markets can use a different table or settlement method. Use the rules displayed for the exact market rather than applying this illustration automatically.

Rule 4 and Matched Betting

Rule 4 creates extra risk in matched betting because the bookmaker back bet and exchange lay bet may not be adjusted in the same way. A screenshot that showed closely matched prices before a withdrawal does not prove that the final settled positions still balance.

• Do not reuse the original lay stake after either side has changed its settled price.
• Check whether the exchange removed the runner, reduced matched odds or cancelled unmatched offers.
• Check whether the bookmaker used the same withdrawal price and timing as the exchange.
• Re-enter the final effective prices in the matched betting calculator before placing any corrective bet.

The broader matched betting guide explains how the back and lay sides work. Rule 4 is one reason a nominally covered position can still produce an unexpected loss if the settlement rules are not aligned.

Sportsbook Rule 4 vs Exchange Reduction Factors

A sportsbook commonly applies a Tattersalls-style deduction to fixed-odds winnings. A betting exchange can instead adjust matched prices using a reduction factor assigned to the withdrawn runner. The current sportsbook horse-racing rules and exchange horse-racing rules describe these as separate settlement systems.

On an exchange, win-market and place-market adjustments can also be calculated differently. Matched and unmatched bets may receive different treatment, and material late withdrawals can trigger cancellations or post-race adjustments. That is why copying a sportsbook Rule 4 percentage directly onto an exchange price can produce the wrong answer.

If you compare the cost of different exchange positions, the exchange commission calculator can calculate commission after settlement. It does not replace the reduction-factor step.

How to Check a Rule 4 Settlement

1. Save the original receipt. Record the stake, price, bet time and market.
2. Identify every non-runner. Note the official withdrawal time and status.
3. Find the recorded withdrawal price. This determines the relevant deduction band under many rules.
4. Read the product-specific rule. Sportsbook, exchange, each-way and place-only markets may differ.
5. Recalculate profit, not just return. Keep the original stake separate unless the published rule says otherwise.
6. Compare your result with the settlement statement. If they differ, ask the operator to identify the withdrawal price and rule used.

A useful dispute is specific: it names the bet, the non-runner, the recorded price, the published rule and the arithmetic. A vague complaint that the odds changed is harder to resolve because an adjustment can be legitimate while the amount or timing is still wrong.

Common Rule 4 Mistakes

• Deducting from the full return: the standard calculation deducts from profit, then adds the stake back.
• Using your selection's price: the table is driven by the withdrawn runner's applicable price.
• Ignoring a reformed market: bets placed after reformation should be assessed under the later market.
• Assuming all products share one rule: sportsbook, exchange, ante-post and place-only treatment can differ.
• Leaving a matched bet untouched: a withdrawal can change both the back return and the lay liability.

Rule 4 Betting FAQs