Double After Split (DAS) in Blackjack
What it means
When you split a pair, you play two hands. Double after split, or DAS, means you can double down on either of those new hands after you receive your next card. Without it, you can only hit or stand.
DAS is good for you. It is common in modern shoe games and often missing in single deck games.
What it is worth
A table that does not allow double after split adds 0.14 to the house edge. That is one of the larger rule penalties, in the same range as dealer hitting soft 17, which adds 0.22. You can see all of them in the rules overview.
Which plays depend on it
Some pairs are only worth splitting because DAS lets you double the new hands. In a 6 or 8 deck game, with DAS you split:
- 2,2 and 3,3 against a dealer 2 or 3.
- 4,4 against a 5 or 6.
- 6,6 against a 2.
Without DAS, play each of those as a hit. The chart codes this way: "split if DAS, otherwise hit." The thinking is simple. You split a weak pair against a weak dealer card hoping to draw a 10 or 11 and double. If you cannot double, the split is not worth it.
In a single deck game without DAS, 4,4 against a 5 or 6 is a double rather than a hit. See single deck strategy.
Other splitting rules
- Resplitting. Many tables let you split up to 4 hands total. Limiting you to 3 hands adds only 0.01, but allowing no resplit at all adds 0.10.
- Resplitting aces. Most tables let you split aces once and give one card per ace. If they also allow you to resplit aces, the house edge falls by 0.08.
- Doubling limits. Some tables allow doubling only on 10 and 11 (adds 0.18) or on 9 through 11 (adds 0.09). Those limits also affect hands you double after splitting.
Strategy tips
- Always split aces and eights, with or without DAS.
- Never split tens or fives. Two fives are hard 10, which you double. Two tens are 20.
- Check the DAS rule before you sit. If the felt does not say, ask.
- Do not stop splitting just because doubling is not allowed on a hand. Use the chart for your game.
Open the trainer, turn DAS on and off in Settings, and watch the pair chart change. The basic strategy guide covers how to read the pair section.
Common questions
Is DAS the same as doubling on any two cards?
No. DAS is about doubling on the hands you made by splitting. Doubling on any two cards is about your first hand.
Can I double after splitting aces?
Usually not. Split aces typically get one card each and no more actions.
Which is worse, no DAS or H17?
H17 adds 0.22 and no DAS adds 0.14, so H17 costs more.
How do I know if a table allows DAS?
The rules are often printed on the felt or on a sign. If not, ask the dealer.