Checkback after 2NT jump rebid by Opener

After Opener jump rebids 2NT then 3 becomes Checkback. We jump rebid 2NT to show 18-19 HCP with a balanced hand.

Example 1

1	Pass	1	Pass
2NT	Pass	3*	Pass
?

* 3 is Checkback. Responses are:

• 3 shows 4 hearts and 3 spades
• 3 shows 4 hearts and denies 3 spades
• 3 shows 3 spades and denies 4 hearts
• 3NT denies 4 hearts or 3 spades

Example 2

1	Pass	1	Pass
2NT	Pass	3	Pass
?

Responses are:

• 3 shows 4 hearts and 4 spades
• 3 shows 4 hearts and denies 4 spades
• 3 shows 4 spades and denies 4 hearts
• 3NT denies 4 hearts or 4 spades