Player Injury Rules: How Sportsbooks and Prediction Markets Handle Injured Players

A player getting hurt changes everything about your bet, but how it changes depends entirely on where you placed it. Regulated US books now offer formal injury protection programs. Offshore books mostly stick to the participation rule. Prediction markets don’t void anything — prices just move. The rules differ by platform, by sport, and by bet type. They also change over time. This guide covers all of it.

Why Injury Rules Matter More Than You Think

Player props are the fastest-growing segment in sports betting. More prop volume means more exposure to the single most unpredictable event in sports: a player getting hurt.

You lock in a receiver over 65.5 receiving yards. He catches one pass in the first quarter, tears his hamstring, and never returns. Your bet was on pace to hit. Instead, it’s graded as a loss with 12 receiving yards. Is that fair?

The answer depends on who you ask — and more importantly, where you placed the bet. Sportsbooks, offshore books, and prediction markets each handle this scenario differently. Some void the bet. Some refund it under specific conditions. Some grade it as a loss regardless. And prediction markets don’t even have a “void” mechanism — your contract settles on the stats that happened, period.

If you’re building a betting agent that trades player props across platforms, these differences aren’t an edge case. They’re a core risk parameter your system needs to model.

The Core Rule: Participation = Action

Across all sportsbooks — regulated, offshore, and everything in between — one principle holds:

If the player doesn’t participate, the bet is voided. If the player takes the field, the bet stands.

This is the participation rule, and it applies universally as the baseline. The disagreements start at the edges: What counts as “participation”? What happens when a player checks in for 30 seconds and immediately exits? Does the book have any injury protection beyond the baseline?

Here’s how “participation” is defined across major sports:

Once a player crosses that participation threshold, the bet has “action” — and on most platforms, it will be graded on actual performance regardless of what happens next.

Regulated US Sportsbooks: The New Injury Protection Era

The regulated US market has shifted significantly since 2024. Two major programs now exist that go beyond the basic participation rule.

Fanatics Sportsbook — Fair Play Policy

Fanatics launched its Fair Play policy in 2024, and it was the first major US sportsbook to offer systematic injury protection. The policy covers player prop bets across NFL, NBA, MLB, NHL, WNBA, MLS, international soccer, golf, and tennis.

How it works:

• Single bets: If a player exits within the qualifying window and doesn’t return, the bet is voided and your stake is refunded. “Under” props may be graded as wins.
• Parlays/SGPs: The injured player’s leg is voided, odds are recalculated, and the remaining legs stay live.
• Automatic: No forms, no customer service calls. The Fanatics trading team monitors injuries in real time and applies refunds automatically.

Sport-specific qualifying windows:

Real example: During the 2025 NBA Playoffs, Stephen Curry exited Game 1 of the Western Conference semifinals against Minnesota in the second quarter with a hamstring injury. Fanatics automatically refunded over $500,000 in bets on Curry’s performance. One Michigan bettor had a $5,000 four-leg parlay — with Curry’s leg voided and the remaining legs cashing, the payout was $224,773.

DraftKings — Early Exit Program

DraftKings launched Early Exit in August 2025 ahead of the NFL season. The structure is similar to Fanatics Fair Play but with some differences in timing windows and payout mechanics.

How it works:

• Single bets: You receive cash credits equal to your original stake (not a direct refund — credits may affect bonus/promo tracking differently).
• Parlays/SGPs: The injured leg is removed and odds recalculated based on remaining selections.
• Automatic: No promo code or customer service contact needed.

Sport-specific qualifying windows:

Important exclusions from Early Exit:

• Live/in-play player props don’t qualify
• Props already settled before the injury (player hit the over) don’t qualify
• “Under” props settle as wins (they pay out regardless)
• Players removed for performance, ejection, or coaching decisions don’t qualify (exception: NBA/WNBA considers any early exit, not just injury)
• Players injured outside the qualifying window (e.g., second half) don’t qualify

Real example: In Game 7 of the 2025 NBA Finals, Indiana Pacers guard Tyrese Haliburton suffered a torn Achilles early in the first quarter. Despite having already made three three-pointers, he couldn’t continue. DraftKings voided certain prop bets (assists, rebounds) related to Haliburton’s performance — this was actually before the formal Early Exit program but demonstrated the approach the book would later codify.

BetMGM

BetMGM follows the strict participation rule with no formal injury protection program. If a player is ruled out before the game, the bet is voided. Once a player takes one snap, the bet has action and will be graded based on actual stats — even if the player exits 30 seconds later.

For parlays: a leg with a player who gets hurt mid-game is not voided. The leg stays live and is graded on actual performance, which means a mid-game injury can sink your entire parlay.

BetMGM has occasionally made exceptions during high-profile events, but there is no published, systematic policy that bettors can rely on.

Caesars Sportsbook

Caesars follows the same strict approach: no participation = void, any participation = live bet. No injury refund program exists. Once a player checks in, the bet holds even if the player is hurt seconds into the game.

Hard Rock Bet

Hard Rock Bet introduced a Player Injury Insurance promotion for NFL and NBA during the 2025-26 season. This is structured as a seasonal promotion with defined start and end dates (not a permanent house rule), which means it could be modified or discontinued at any time.

Offshore Sportsbooks: The Participation Rule, No Safety Net

Offshore books don’t offer injury protection programs. They stick to the participation rule but define it differently across platforms.

The Bovada 3-minute rule is notable — it’s more generous than most regulated books’ baseline participation threshold. If your player checks in, takes one snap, and immediately exits at Bovada, the bet is voided because the 3-minute threshold wasn’t met. At BetMGM, that same bet has action.

No offshore book offers anything comparable to DraftKings Early Exit or Fanatics Fair Play. If you’re betting player props at offshore books, you absorb the full injury risk once the player meets the participation threshold. This is one of the practical trade-offs between offshore and regulated sportsbooks — the regulated market is increasingly competing on bettor-friendly features that offshore operators haven’t matched.

For more on offshore sportsbook API access and data availability, see the Offshore Sportsbook API Guide.

Prediction Markets: No Void, No Refund, Just Markets

Prediction markets handle injuries fundamentally differently than sportsbooks. There is no house. There is no void button. There is no injury protection program.

Polymarket

Polymarket is a peer-to-peer exchange. Player prop markets resolve based on official box score statistics — full stop. If your player exits in the first minute, the market still resolves on the actual stat line.

What does change is the price. When injury news breaks, traders immediately sell their positions on the injured player’s “over” contracts and buy “under” contracts. The price moves organically to reflect the new reality. This creates both risk and opportunity:

• Risk: If you’re holding an “over” contract and the player gets hurt, you can sell — but you’ll sell at a loss because the price has already dropped. There’s no refund.
• Opportunity: If you see injury news before the market fully reprices, you can trade on it. This is a core use case for prediction market trading bots that monitor injury feeds via API.

The dispute mechanism exists on Polymarket (via UMA’s Optimistic Oracle for international markets, or the internal Markets Team for US markets), but it’s designed for resolution disputes — not injury grievances. If a market’s resolution criteria say “resolves based on official box score stats,” an injury doesn’t change the resolution criteria.

For developers building on the Polymarket CLOB API, the implication is clear: your agent needs to price in injury risk before entering a position, and it needs to monitor injury feeds to exit positions when news breaks.

Kalshi

Kalshi’s approach to injuries has caused real losses for traders who assumed sportsbook-style rules would apply. Per Kalshi’s market rules for player props:

Once a player has taken at least one snap, the Contract will settle based on actual statistics accumulated despite any in-game injury, ejection, or other removal from the game.

That much is familiar. The sharp difference comes when a player never plays at all. At most sportsbooks, “Did Not Play” = void. At Kalshi, the platform may settle the market at its last traded fair price — the exchange-determined estimate of fair value immediately before the disqualifying event became known.

One trader publicly documented losing $30,000 after a tennis match was cancelled and Kalshi resolved the market at the last traded price rather than voiding it. The trader expected the sportsbook norm of DNP = void. Kalshi’s contract language said otherwise.

Kalshi is a CFTC-regulated designated contract market, and its settlement rules are filed with the CFTC. The platform can also invoke Rule 6.3(c) to settle at last traded price when an outcome is deemed unresolvable. Traders can submit a “Request to Settle” but it’s advisory — Kalshi’s internal markets team makes the final determination.

For a deeper comparison of how Kalshi and Polymarket resolve edge cases, see the Prediction Market API Reference.

Comparison Table: Injury Handling Across All Platform Types

Sport-Specific Nuances

Tennis and Golf: Individual Sports, Bigger Impact

In individual sports, an injury affects every market — not just player props. If a tennis player retires mid-match, it changes the match winner outcome, set scores, game totals, and every derivative market.

Most sportsbooks void moneyline and spread bets if a player retires before the match is complete. The specific rules vary:

• Some books require the first set to be completed for the bet to have action
• Some void all pre-match bets on retirement regardless of when it happens
• Live bets placed after the injury typically stand

Golf withdrawals follow similar logic: if a player withdraws before completing the round, most books void individual round bets. Tournament-winner futures typically stand — the player simply doesn’t win.

Prediction markets generally resolve these based on the official result. If a player retires, the opponent wins the match. The contract pays out accordingly.

MLB: Pitcher vs. Hitter Distinction

MLB has unique rules because pitchers and hitters have different participation thresholds:

• Pitchers must throw at least one pitch for the bet to have action. If a starting pitcher is scratched before the game, pitcher-specific props are voided.
• Hitters must record at least one plate appearance. A pinch-hit at-bat counts.

The “opener” strategy (where a relief pitcher starts and the planned starter enters in the second inning) creates additional complexity. If you bet on the “starting pitcher” and the team uses an opener, most books void the bet.

NFL: Inactive Lists and Late Scratches

NFL teams release inactive lists 90 minutes before kickoff. Books typically remove props for inactive players and void any existing wagers. But the 90-minute window creates a gap where a player can be downgraded from “questionable” to “out” after you’ve already placed your bet.

Sharp bettors monitor the inactives closely. For agents, this means tracking the NFL’s official injury report API and reacting within the 90-minute window. See our sharp betting guides for more on exploiting information edges around injury reports.

The Agent Infrastructure Angle

For developers building autonomous betting agents, injury rules create both a risk management requirement and an alpha opportunity.

Risk management: Your agent needs to know the injury policy for every platform it trades on. If it holds a player prop position on Polymarket, it can’t assume a sportsbook-style void — it needs to monitor injury feeds and exit the position via the market. If it trades on Kalshi, it needs to understand that DNP doesn’t mean void. A single missed rule difference can result in five-figure losses.

Alpha opportunity: Injury information propagates at different speeds across platforms. A regulated sportsbook might pull player props within seconds of a late scratch. Polymarket’s price might take 30-60 seconds to fully adjust as human traders react. An agent monitoring real-time injury feeds (NFL’s official API, team Twitter accounts, beat reporter feeds) can trade the gap.

A practical agent architecture for injury-aware trading:

┌──────────────────────┐
│  Injury Feed Monitor  │  ← NFL API, team feeds, beat reporters
│  (Layer 4 — Intel)    │
└──────────┬───────────┘
           │ injury_event
           ▼
┌──────────────────────┐
│  Position Scanner     │  ← Check open positions across all platforms
│  (Layer 3 — Trading)  │
└──────────┬───────────┘
           │ affected_positions[]
           ▼
┌──────────────────────┐
│  Platform Rules Engine│  ← Know void/settle rules per platform
│                       │
│  Sportsbook: wait     │  (may auto-void)
│  Polymarket: exit     │  (sell position via CLOB)
│  Kalshi: exit or hold │  (depends on contract terms)
└──────────┬───────────┘
           │ trade_actions[]
           ▼
┌──────────────────────┐
│  Execution Layer      │  ← Place exit trades via API
│  (Layer 2 — Wallet)   │
└──────────────────────┘

For the full framework on how identity, wallets, trading, and intelligence layers connect, see the Agent Betting Stack.

These Rules Change — Check Before You Bet

This point is critical enough to call out explicitly: injury rules are not permanent.

• DraftKings didn’t have Early Exit until August 2025. Before that, injury refunds were handled case-by-case at the operator’s discretion.
• Fanatics Fair Play launched in 2024 and has been updated with sport-specific windows and postseason adjustments.
• Hard Rock Bet’s Player Injury Insurance is structured as a seasonal promotion with defined expiration dates.
• Kalshi’s settlement mechanics for player props are defined in CFTC-filed contract terms that can be amended.
• Polymarket’s resolution criteria are set per-market and can vary between similar markets.

Before placing any player prop bet, check the current house rules for your specific platform and sport. On regulated books, search for “[sportsbook name] house rules” — they’re publicly posted but often hard to find within the app. On prediction markets, read the resolution criteria on the individual market page.

For offshore books, house rules are typically in the site footer or help section. See our offshore sportsbook reviews for direct links to each book’s rules.

What’s Next

• Offshore vs. Regulated Sportsbooks — Full comparison for developers, including API access and data availability
• The Agent Betting Stack — Four-layer framework for building autonomous betting agents
• Prediction Market API Reference — Side-by-side Polymarket and Kalshi endpoints
• Sharp Betting Guides — Advanced strategies for information-edge betting
• Best Sportsbook Odds by Sport — Vig rankings across NFL, NBA, MLB, NHL