Insurance is offered every time the dealer shows an ace. Casinos frame it as protecting your hand, but the math tells a different story. Here's exactly when to take it, when to decline, and why most players get this wrong.
When the dealer's upcard is an ace, before peeking at the hole card, the dealer offers insurance to all players. Insurance is a side bet worth up to half your original bet. It pays 2:1 if the dealer has blackjack (a 10-value card in the hole). If the dealer does not have blackjack, you lose the insurance bet and play continues normally.
You bet $20. Dealer shows an ace. You take insurance for $10. If the dealer has blackjack: you lose your $20 original bet but win $20 from the insurance (2:1 on $10). Net result: push. You break even. If the dealer does not have blackjack: you lose the $10 insurance bet and play continues on your $20 hand.
The insurance bet is essentially a separate wager that the dealer's hole card is a 10-value card (10, J, Q, or K). In a 6-deck shoe, there are 96 ten-value cards out of 312 total cards. That's a 30.77% chance the dealer has blackjack.
A 7.4% house edge is worse than roulette. Insurance is one of the worst bets at the blackjack table. The casino markets it as protection, but it's actually a separate, bad side bet that happens to be offered at the same time as your main hand.
For any player using basic strategy without card counting, the correct play is always to decline insurance regardless of what cards you hold, what your bet is, or how many times the dealer has had blackjack recently.
Past hands do not matter. The probability resets every hand. The fact that the dealer just had blackjack twice in a row does not increase or decrease the chance they have it again.
Some players take insurance when they have 20 or blackjack to "protect" their hand. This does not change the math. Insurance is always a 7.4% house edge bet in a neutral shoe. What you're holding is irrelevant to whether the dealer has a ten in the hole.
When you have blackjack and the dealer shows an ace, the casino may offer "even money," a guaranteed 1:1 payout instead of the usual 3:2. This sounds safer, but even money is mathematically identical to taking insurance with a blackjack hand.
Declining even money and risking a push (if the dealer also has blackjack) is the correct play for the same reason: the 3:2 payout on your blackjack is worth more in expected value than the guaranteed 1:1, because the dealer has blackjack less than 33.3% of the time. Decline even money.
Insurance becomes profitable when the shoe is rich enough in ten-value cards that the dealer's chance of having blackjack exceeds 33.3%. Using the Hi-Lo counting system, this happens at a true count of +3 or higher.
Blackjack GTO automatically shows whether the count supports taking insurance. When the insurance popup appears, the count panel tells you the true count and whether to take or decline based on the Hi-Lo index.
Note: this is one of the most well-known index plays, which means casinos watch for players who only take insurance at high counts. In a live casino, mix in occasional incorrect insurance decisions at high counts if you're concerned about heat.
Blackjack GTO shows the insurance popup with the current true count every time the dealer shows an ace and tells you whether to take or decline based on the count. No money, no sign-up.
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