Rule 4 Horse Racing Guide: Complete Irish Bettors’ Handbook (2026)

Dec 8, 2025 – 7 min read
Betting Academy

What is a Rule 4 Horse Racing?

Rule 4 is a deduction from your winnings (not your stake) when a horse is withdrawn after final declarations. It cuts your profit by a set percentage based on that horse’s odds, because your pick now has a better chance in a smaller field.

For example, if you backed a horse at 4/1 for €20 and a 3/1 rival was withdrawn (25c Rule 4), your €80 profit is reduced by €20, giving €60 profit plus your €20 stake = €80 total return.

Key Takeaways

Rule 4 adjusts fixed-odds bets when a horse is withdrawn post-declaration, using a standard deduction table tied to the withdrawn horse’s price.
Deductions apply only to profit, can be cumulative, are capped at 90c, and do not apply to Ante-Post bets, waived 5c outsiders, or bets placed after the market is reformed.
Features like Cash Out and BOG (Best Odds Guaranteed) adapt automatically: Cash Out drops instantly after a Rule 4, and BOG compares the price deducted with SP to settle at the higher value.

Rule 4 and other rules are clearly displayed on Irish-licensed modern betting platforms, such as Betmaster, which offers a streamlined, convenient Horse Racing betting experience with transparent, competitive odds.

The Logic in Brief

Fewer Horses = Higher Probability: When a horse withdraws, the statistical probability of the remaining horses winning increases.
Price Adjustment: The odds secured before the withdrawal no longer reflect the new, smaller field size.
Balancing the Book: Bookmakers apply a deduction to the winnings (not the stake) to align with the revised probability of the race.

Key Fact: Rule 4 is a mathematical recalculation to maintain market integrity for both backers and layers.

When are Rule 4 deductions applied?

Rule 4 applies only under specific conditions listed below:

Time of Bet: Was the bet placed after the final declarations (typically 10:00 AM on the day before or morning of the race)?
Timing of Withdrawal: Was a horse withdrawn after the bet was placed?
Market Status: Was a fixed price (Early Price or Board Price) taken before the market was reformed?

If the answer is YES to all three, a Rule 4 deduction likely applies.

1 -
X -
2 -
+156

1 -
X -
2 -
+156

1 -
X -
2 -
+156

Regulatory Context (2026)

Under the Gambling Regulatory Authority of Ireland (GRAI), licensed operators must apply these rules transparently. The specific deduction is typically listed in the bet settlement notes of an online bet slip. Always bet responsibly and utilise available tools, such as the National Gambling Exclusion Register, when managing betting activity is required.

The Rule 4 Deduction Table – 2026 Standard

The deduction size depends entirely on the odds of the withdrawn horse at the time of withdrawal.

Strong Favourite Withdrawn: Higher deduction (e.g., 40c–50c).
Outsider Withdrawn: Lower or no deduction.

Deduction Per €1 of Winnings:

Odds of Withdrawn Horse (Fractional)	Odds (Decimal)	Deduction (Cents in €)
1/9 or shorter	1.11 or lower	90c
2/11 to 2/17	1.12 – 1.18	85c
1/4 to 1/5	1.20 – 1.25	80c
3/10 to 2/7	1.29 – 1.30	75c
2/5 to 1/3	1.33 – 1.40	70c
8/15 to 4/9	1.44 – 1.53	65c
8/13 to 4/7	1.57 – 1.62	60c
4/5 to 4/6	1.67 – 1.80	55c
20/21 to 5/6	1.83 – 1.95	50c
Evens to 6/5	2.00 – 2.20	45c
5/4 to 6/4	2.25 – 2.50	40c
13/8 to 7/4	2.63 – 2.75	35c
15/8 to 9/4	2.88 – 3.25	30c
5/2 to 3/1	3.50 – 4.00	25c
16/5 to 4/1	4.20 – 5.00	20c
9/2 to 11/2	5.50 – 6.50	15c
6/1 to 9/1	7.00 – 10.00	10c
10/1 to 14/1	11.00 – 15.00	5c*
Over 14/1	Over 15.00	No Deduction

*Market Note: Certain Irish operators may waive the 5c deduction as a standard concession.

How to Calculate a Rule 4 Deduction?

Once you understand how Rule 4 affects deductions, it becomes easier to evaluate staking approaches such as NAP selections, where confidence levels and potential returns take on a clearer context.

Follow these three steps to calculate the exact return.

The Scenario:

Bet: €20 on Horse A at 4/1 (5.0).
Withdrawal: Horse B (priced at 3/1) is withdrawn.
Reference: A 3/1 withdrawal equals a 25c deduction.

Step 1: Calculate Potential Profit

€20 Stake x 4/1 Odds = €80 Potential Profit.

Step 2: Apply the Deduction Percentage

Take 25% (25c in the Euro) off the profit. €80 x 0.25 = €20 Deduction.

Step 3: Determine Final Settlement

Original Profit (€80) – Deduction (€20) = €60 New Profit. Add back the Stake (€20). Total Settlement: €80.

App Feature

Betmaster automatically updates the Open Bets slip. If a Rule 4 applies, the “Potential Returns” figure often adjusts dynamically before the race commences.

Does Rule 4 affect the payout?

Yes, but strictly the profit component. The original stake is ring-fenced. Deductions apply only to the profit portion of the bet.

Win Bets: Deduction applied to net profit.
Each-Way Bets: Deduction applied to both the “Win” and “Place” profit separately.

With the impact of Rule 4 clarified, you may also want to look at each-way betting, since deductions can influence both place terms and the overall value of a wager.

Rule 4 Exceptions & Concessions

Not every withdrawal triggers a deduction. These are the primary exceptions:

1. Ante-Post Bets

Rule 4 does not apply to bets placed on an Ante-Post market (before final declarations).

The Dynamic: If the selected horse withdraws, the stake is lost. If a rival withdraws, the odds remain locked without deduction.

2. The 5c Waiver

Although the official rule permits a 5c deduction for horses priced 10/1 to 14/1, many competitive Irish sites waive this. If an outsider withdraws, the settlement often remains unaffected.

3. Reformed Markets

If a bet is placed after the market has been reformed (meaning the withdrawn horse has been removed and new odds issued), no Rule 4 applies regarding that specific withdrawal.

Advanced Scenarios

What happens if more than one horse is withdrawn?

Deductions are cumulative but capped.

Scenario: Horse A (15c deduction) and Horse B (10c deduction) withdraw.
Result: A 25c total deduction applies.
The Cap: The maximum possible deduction is 90c in the Euro. At least 10% of the winnings plus the stake will always be returned.

How does Rule 4 affect Cash Out?

Cash Out values derive from the live potential settlement. If a Rule 4 is declared, the Cash Out offer is immediately reduced to reflect the reduced potential profit.

Will Best Odds Guaranteed (BOG) still apply?

Yes, but the calculation follows a specific order. Bookmakers settle on the higher value between the following:

The Taken Price minus the Rule 4 deduction.
The Starting Price (SP) (which requires no deduction as it is based on the final field).

Example:

Taken Price: 4/1. A 20c Rule 4 adjusts the effective odds to 3.2/1.
Starting Price: The horse wins at an SP of 3.5/1.
Result: Settlement occurs at 3.5/1 (SP) as it exceeds the price taken after the Rule 4 deduction has been applied.

NON RUNNERS: Summary Checklist

If the bet is…	And a horse withdraws…	The Outcome
Ante-Post	Any price	No Deduction
Day of Race	Price 14/1 or bigger	No Deduction
Day of Race	Price shorter than 14/1	Rule 4 Applies
After Market Reform	Any price	No Deduction

FAQ

What’s a rule 4 in horse racing?

Rule 4 is a market adjustment mechanism. It reduces payouts on winning bets when a horse is withdrawn, compensating for the increased statistical probability that the remaining horses will win.

How to calculate a Rule 4?

Identify the odds of the withdrawn horse in the Rule 4 Deduction Table. Convert the deduction (e.g., 20c) into a percentage (20%). Calculate the potential profit (excluding stake) and subtract that percentage. Add the stake back to determine the final settlement.

What is the rule 4 for 30p?

A 30p (or 30c) Rule 4 deduction applies when the withdrawn horse was priced between 15/8 (2.88) and 9/4 (3.25). This necessitates a 30% deduction from the winnings of any bet placed before the market reformation.