Takeout Double - Requirements

Requirements

Commonly double is considered takeout whenever one of the following conditions is met (but see balancing double below):

• Opponents have previously bid only one suit, and the player did not have chance to double that suit before.
• Opponents have previously bid two suits, and partner has passed.
• Opponents have found a fit.

Most common requirements to make a takeout double are:

• Shortness (doubleton or less, tripleton at most) in the opponents' suit(s),
• Length (at minimum 3 cards, preferably 4) in the unbid suits,
• High-card point strength of at least a minimal opening bid (11 HCP)

The most common treatment is that the fewer high card points the hand possesses, the more strict are the distribution requirements (i.e. opponent's suit(s) shorter and unbid suits longer). Most players play that hands with 17-18 high card points should double regardless of distribution (unless the hand is suitable for 1NT overcall). Also, more high-card strength is required when opponents have bid on higher levels (e.g. preempted). Most players play that a double up to the level of 4♥ is takeout, while doubles on higher levels are for penalties or "cooperative" (i.e. the partner is supposed to pass unless his distribution and/or strength indicates that playing a contract of their own on a higher level is a better prospect).