After our side opens 1NT, there are many possible ways to go. At the end of this introductory article are links to more complicated issues.
The easy part of the responses to 1NT:
2
= Stayman
2
= Jacoby Transfer (5+
)
2 = Jacoby Transfer (5+
)
After that, you can consult the links at the end of this short article.
Stayman should be used only with game invitational strength. Exception: Responder can be very weak and intend to pass anything opener does (this means responder has to be prepared to play in 2, so can use Stayman, with say: 5432 5432 65432 --.)
Transfers can be made with 0 points. With a hand like:
987643 
43 
97 
982,
you are better off (even on the 2 level) with spades trump than to table this dummy in 1NT. Since transfers do not promise any points, the 1NT opener MUST accept the transfer (by bidding the suit responder has shown). Responder is in charge and opener does as told.
If responder transfers followed by a new suit on the 3-level, it is natural and forcing to game (example: 1NT-2-2-3). If responder transfers and bids 3-of-the-suit he has shown, it is invitational with 6-cards in the trump suit (example:1NT-2-2-3). If responder transfers and bids 2NT, it is invitational with only five cards in the suit shown (example: 1NT-2-2-2NT). With a game forcing hand and five-of-a-major and no second 4-card suit, responder transfers on the two level and then bids 3NT to give the 1NT bidder a choice of games (example: 1NT-2-2-3NT).
With 5-4 in the majors and enough for game, start with Stayman. Then, if partner bids 2, you can jump in the suit with 5-cards (or the other suit, if you play Smolen) -- example: 1NT-2-2-3.
With 5-5 in the majors and enough for game, start by transferring to spades, then bidding hearts -- 1NT-2-2-3.
Make sure you know if your partnership uses Texas Transfers as this can change the meaning of a transfer followed by a jump to 4-of-the-major.
While most intermediate players have used Transfers for a long time, the follow-ups can still cause difficulty.
BMS Webinar on Responses to 1NT
Further discussion:
Filling out the Convention Card after 1NT
Updated Dec 2022