I’m going to assume six decks, dealer hits a soft 17, double after split, surrender, and re-splitting aces. If double for less is not allowed then I get a player edge of 4.9%. Here is that correct strategy. Obviously, this strategy may set off some red flags. If double for less is allowed, then I get a maximum player edge of 9.4% with the following strategy. When doubling for less, bet as little extra as possible, preferably just one penny. My 9.4% figure assumes a tiny double down wager. In reality, most casinos require doubling with at least the table minimum. This question was raised and discussed in the forum of my companion site Wizard of Vegas.