Consider the following everyday hand:
Q109xx
Axx
xx
KJ10
Partner deals and opens 1, you reply 1 and partner rebids 1N, showing a balanced hand with 15-16 points. What do you bid now? You have 25-26 points between you so you should certainly be in game, but which game is best? Your diamonds won’t help to stop the suit, and if you just punt 3N then a diamond lead (knocking out partner’s guard before he can set up 9 tricks) could kill the contract. If partner has a 5-card heart suit then 4 could easily play better (using the Axx of trumps in dummy to ruff declarer’s diamond losers). Similarly if partner has 3 spades then 4 could be on. How do you find the best game to play in?
A useful method of doing this is the checkback convention. It does away with a natural 2 after a 1N rebid in much the same way as the Stayman convention does away with a 2 takeout after a 1N opening.
After a 1N rebid, 2 asks partner to reveal any extra length he has not yet shown in the majors, i.e. either a fifth card in a major he has already bid, or 3 card support for your major (I assume partner would raise you with 4 card support!), or an unbid 4 card major. This helps you to find an 8 card fit in a major.
Partner should bid his “extra” majors up the line (i.e. show hearts first if he has both majors) and 2 if he has no more major-suit length than he has already shown.
As with bidding Stayman over a 1N opening, when you bid Checkback over a 1N rebid you should be prepared for every possible response (2, 2 and 2).
The kind of hand on which you should use Checkback is a balanced 9+ with extra major-suit length (settling for 3N if you don’t have an 8 card major fit and bidding 4 of the major in which you do have an 8 card fit); or a fairly weak hand with both majors (at least 5-4) that you feel will play better in 2 of a major than in 1N (if partner bids 2 in response to Checkback then you pull to 2 of your 5-card major).
That’s enough waffle, here are some example auctions (N.B. * = Checkback and + = no extra major suit length):
1. West East West East
AJx Q109xx 1 1
KJ10x Axx 1N 2*
QJx xx 2 4
Axx KJ10
OK, 4 is a thin game, but 3N could be cold off on a diamond lead.
2. West East West East
AJx Q10xx 1 1
KJx Axxx 1N 2*
QJx Kx 2 3N
West shows his 3 card heart support, but this does not help East who settles for 3N.
3. West East West East
AJxx Q10xx 1 1
KJx Axxx 1N 2*
Kx Qxx 2 3N
Axxx Qx 4
West shows his 3 card heart support first (bidding his suits up the line). East’s jump to 3N shows West he had 4 spades (otherwise why bid Checkback at all?) and West tries 4 instead.
4. West East West East
AJx Q10xx 1 1
KJx Axx 1N 3N
QJx Kxxx
Axxx J10
East has no need to use Checkback and settles for 3N.
5. West East West East
AJx Q10x 1 1
KJ A10xxx 1N 2*
QJxx Kx 2+ 3N
Axxx J10x
West has only 2 card support (albeit good 2 card support) for partner’s hearts and no spade suit to introduce. East (who would go to 4 if West had 3 hearts) settles for 3N.
6. West East West East
AJx Qx 1 1
KJ A10xxxx 1N 4
QJxx Kx
Axxx J10x
No need for Checkback; East can confidently bid 4 with a 6 card suit opposite partner’s announced 2.
7. West East West East
AJx Qxxx 1 1
KJ A10xxx 1N 2*
QJxx xxx 2+ 2
Axxx x
East looks for a major suit fit having no help in the minors, settling for a 5-2 fit (in hearts) when West denies 4 spades.
Of course the convention can be used for other ranges of 1N rebids; e.g. playing a strong no trump (where a 1N rebid would show 12-14 points), use Checkback to find the best game when you are responding with 11+ points.
So there you are; Checkback is a simple gadget to use and very effective. Why not give it a try?