What happens to doubles and splits when dealers have blackjacks?

Question: At blackjack, you might split pairs, then double down on one or more of the hands when the dealer has an ace or 10 showing. This means you might have multiple bets on the table. If the dealer doesn’t check in advance for a blackjack and ends up getting one, you only lose some of this. How much do the dealers take, and why don't they get it all?

Answer: In many casinos today, dealers check their hole cards when they have 10s or aces showing, using readers mounted on the tables, to indicate whether they have blackjacks. If so, they don’t play out the round because it wouldn't matter what anybody else did. Any player who also had a blackjack would "push;" all others would lose their bets. The rules of the game are set up so players who follow perfect "basic strategy" give the casino a certain small edge. These rules and the corresponding values of house edge assume that nothing happening during a round is relevant if the dealer has blackjack.

In casinos that don't peek, rounds are played out. However, if dealers have blackjacks, they therefore collect as though the decisions were made in advance. So players who split or double only lose their initial bets - whatever was on the table when the cards were first dealt. Money put out during the round, which would not have been in action were the dealer's blackjack known, is returned. Sometimes, after splitting and doubling, you're sitting there with bets on three or four weak hands against a strong dealer's 10 – and you're grateful to see an ace in the hole!