Though the simplest form of blackjack is pretty much the same from table to table and casino to casino, there are a lot of subtle rule variations. To make sure you are following the correct strategy, be sure you know all of the rules ahead of time. If you don’t know, ask. The dealer won’t mind explaining the table rules to you. Often times there is a card or sign that has the rules written out for you. If you are playing online blackjack, read the rules of the game before entering it.
One such rule variation that you might run into regards doubling. In most casinos, you are allowed to double down on any hand. In that case, you should follow basic strategy and double appropriately. However, some blackjack games have rules where you can only double on a nine, ten or eleven. Other blackjack tables only allow you to double on a nine or a ten. For some, you can only double on a ten. The best player odds are in a game where you can double on any card, since taking away any doubling options helps the dealer. The above doubling rules are most common in European casinos.
So what happens if you double when you’re not allowed? Do you just get scolded and told “no?” Sometimes. At some blackjack tables, the dealer will simply tell you that rule is not allowed and ask if you want to hit or stand (and obviously you would hit). At other blackjack tables, though, the penalty for disobeying the doubling rule is a lot worse: It can make you lose.
Let’s just say you have an ace-seven combination versus a dealer 3. The blackjack table only allows you to double on a ten, but you double down anyway, not knowing the rule. You then draw a three and are really excited, because you have just drawn a 21. The dealer then plays out his hand, draws an 18 and then takes your money. You just lost. But how?
You lost because your cards weren’t counted as 21. Because you violated the rule of doubling on only a ten, your ace was counted as a one. Therefore, instead of having A + 7 + 3 = 21, you ended up with A + 7 + 3 = 11. You lost 18 to 11. Not all blackjack tables will penalize you in that way for breaking the doubling rule, but it is quite common, especially in Europe.
What that means is that it is of vital importance to know the exact rules of the exact table at which you are playing. Don’t just say “Yeah, I know blackjack rules” and assume you know the rules of that table. Doing so could cost you money.