Cue bidding after a trump suit has been agreed is a very useful way to help determine whether to bid a slam.  The "non-serious 3NT" is an adjunct to this that makes slam bidding more accurate.

There are different ways to cue bid.  The method I first learnt was to bid a first round control if you have one (ace or void), or miss the suit out if you haven't.  As cue bidding progresses through the suits upwards, you then get the opportunity to bid that suit second time round to show second round control (king or singleton).  This way you can find out if all suits are controlled before you commit to slam.  Inevitably though, by the time you have bid your controls, you are too high to ask for aces.  And partner's void is not the same as an Ace when you have KQx !  Your expected 3 tricks without loss has become just one trick, and half the time only after losing one!

Times change, methods improve, and now people play ace asking bids and after aces have been shown, show specific kings (see Green Aces for such a method).  This improvement means that the commonly adopted method of cue bidding nowadays is that a cue bid shows either first or second round control.  The idea is that if you agree trumps at the 3 level, and you are going on to game, you bid controls upwards such that if all suits are controlled, you can ask for aces.  If both partners have no control in a suit, this implies you have 2 immediate losers in that suit, so there is no point in looking for the slam by asking for aces - even if you have a combined 33 count.

Very useful.  But even this has a big snag.  The snag is - do you want to ask for aces ?  A combined 26 count with flattish hands does not justify it.  Game is enough.

How do you decide whether to ask for aces?  Assume partner has agreed spades as trumps, and you are at the 3 level : he has bid 3♠.  (Maybe Acol 2♠ (strong) 3♠ (game forcing). or maybe 1♠ 2♦ (2 over 1 game force) 2♠ 3♠.)  If you are near minimum you may decide to sign off in game - but partner is unlimited, and you have denied him the opportunity to cue bid.  If he is strong enough, he has to ace ask, and may bid 6♠ with two immediate losers, or sign off in 5♠ and you lose 3 tricks.  If he was allowed to cue bid, this may be prevented.

OK, so don't sign off - perhaps you start cue bidding with 4.  Partner has control in hearts, but not diamonds, so bids 4♥.  You have the missing control in diamonds.  Should you then ace ask, when partner may be a minimum too?  Probably not : you will get too high.  So you bid 4♠.  Now partner has in fact a strong hand, and fails to bid the making slam because he thought there were 2 immediate losers in diamonds !

You can't win - or can you?

This is the problem the "non-serious 3NT" solves.  It applies only when you have agreed a major, so don't want to play in 3NT, and are going on to game or higher.

When you are in a situation in which cue bidding may be about to start, a bid of 3NT, the "non-serious 3NT" gives the message that you have no significant extra values.  For example, you opened 1♠ : 

(a)  you have no long side suit to establish for tricks and are in the 12-14 HCP range.  Over 3♠ you bid 3NT. 

(b)  If over the 3♠ agreement you bypass 3NT and cue bid 4, this therefore implies you DO have some good values, maybe 15-17 HCP.  This is a "serious" cue bid.

See the impact.  You make a serious cue bid of 4.  Partner bids 4♦, you bid 4♥ and partner knows that no suit is wide open.  He can make the decision.  If he is minimum, he can bid 4♠.  You can stop there, and beat the pairs that go one off in 5♠.  If he has some extra values himself, he will ask for aces, as he knows you are serious.  Of course, if he signs off in 4♠ and you were a super-strong 18+ hand you yourself can go on by asking for aces.

This time you are weaker, so make a "non-serious" 3NT bid.  If partner is minimal, or even if he has a fairly strong hand, you have told him you have nothing much to add, so he can safely and simply sign off in game.  If however he still wants to possibly go higher, he makes a cue bid.  You now go along and cue bid any control you have.  You have already told him the message, so your cue bidding does not imply any extra strength - it simply "plugs the holes" to help partner make the right decision whether to go higher than game.

The non-serious 3NT has immediately made the judgement call much more informed.

The rules for the non-serious 3NT :

• If you bid 3NT (having agreed spades) you tell partner you do not have much he doesn't know about.
• You never raise 3♠ to 4♠ if partner is unlimited : you bid the non-serious 3NT.
• If you bypass 3NT and make a serious cue bid, you are showing extra values.  You can then (usually) safely leave the decision to partner.
• If partner bids a non-serious 3NT, you sign off in game unless you are really good, in which case you make a serious cue bid.
• If partner makes a serious cue bid, you always make a cue bid if you can.
• You cue bid the cheapest suit possible.
• If partner has missed a suit, and you have no control there either, you sign off in game as there are 2 immediate losers.

You play "non-serious 3NT" whenever you are going on to game and partner has not limited his strength.  It is up to partnership agreement whether it applies in non-game-forcing situations where partner has limited his hand, such as an Acol 1♠ 3♠.  You could play 3NT as a suggestion to play, but if you choose to play "non-serious" here it implies that you are going on to game anyway, and would be delighted to hear a cue bid from partner if he is toward the upper end of his range, when you will investigate slam.  Conversely, if you bid 4 over 3♠, you have a powerhouse and partner must cue bid even if he is absolute minimum.  Or you can sign off over 3♠ with 4♠, which is a shut-out.

What if hearts are agreed ?

Now you can still use 3NT non-serious, but it makes a cue bid of 3♠ obligatory if you have it.  Whether you are serious or not.  If you don't have it, you make a non-serious 3NT bid or serious 4 cue bid (which denies the spade control).  If partner is the one who makes the ambiguous 3♠ cue bid, then it is you who decides to bid the non-serious 3NT or make a serious cue.

An alternative approach, and my preferred method, is to have a "non-serious 3♠" bid, where 3NT acts as a cue bid of spades.   When hearts are trumps, a bid of 3♠ says nothing about spades, it just says you are non-serious.   A direct bid of 3NT therefore shows a serious hand and a control in spades.

Either way, the "non-serious" 3NT will improve your slam bidding accuracy.

POSTSCRIPT

The "non-serious 3NT" developed from the "serious 3NT" which has the same idea, but reverses the meanings, so that if you bid 3NT you are showing a serious hand, and if you bypass this to make a cue bid, it is non-serious.  The downside of this former approach is that the majority of the time you are non-serious, and partner is too, so when you make a non-serious cue bid he just signs off in game.  This now gives the defence a clue as what not to lead !.  It can also help them in the course of play.  With the "non-serious 3NT", the bidding just goes 3NT 4♠ and the defence is none the wiser. 

submitted by Ray Green