What is Control Cue Bidding in Slam Auctions?

Control Cue Bidding is the practice of bidding unbid side suits above the game level (or on the way to game) to show First Round control (holding an Ace or a void) or Second Round control (holding a King or a singleton) in that suit. Once a trump suit fit has been explicitly agreed, cue bidding allows a partnership to verify that every unbid suit is controlled before committing to a 6 or 7-level slam contract.

Why Control Cue Bidding works

While conventions like Blackwood and RKCB 1430 tell you how many total key cards partner holds, they cannot tell you *which* specific suits those key cards sit in. If your side holds four key cards but both partners lack any control in Diamonds, the defenders can immediately win two fast Diamond tricks the moment they gain the lead, defeating your 6-level slam.

Control Cue Bidding solves this problem by exchanging suit control information step-by-step in economic order. By bidding unbid suits in ascending rank order, partners confirm that no unbid suit contains two fast, unprotected losers.

A worked example: Cue bidding to a safe 6 Spade slam

Spades are agreed as the trump suit after a limit raise.

Opener (South):

♠ A K J 8 2

♥ A Q 4

♦ 7 3

♣ A 2

(19 HCP)

Responder (North):

♠ Q 10 9 4

♥ K 3 2

♦ A K 5 2

♣ 8 4

(12 HCP)

The Auction:

• South: 1♠
• North: 3♠ (Limit raise showing 4-card support and 10–12 HCP)
• South: 4♣ (Control Cue Bid showing 1st or 2nd round Club control)
• North: 4♦ (Control Cue Bid showing Diamond control)
• South: 4NT (RKCB 1430)
• North: 5♦ (0 or 3 Key Cards)
• South: 6♠
• All Pass

*Caption:* South's 4♣ bid shows Club control. North's 4♦ bid shows Diamond control. Because both partners know Hearts are controlled by South's ♥A, South can safely launch 4NT RKCB and bid 6♠ knowing no suit is exposed.

Four common mistakes

• Control cue bidding before a trump suit has been explicitly agreed by the partnership.
• Skipping an unbid suit during cue bidding when you hold control in it (skipping a suit tells partner you hold two fast losers in that skipped suit).
• Confusing a Control Cue Bid with a natural suit bid or a Splinter bid.
• Cue bidding on weak hands that lack slam-invitational strength.

When the rule does not apply

Do not engage in Control Cue Bidding if your hand lacks slam potential opposite partner's bidding; simply bid game in the agreed suit to shut down the auction. Additionally, if your partnership uses Splinter bids, use a Splinter first to describe shortness and support in a single call.

Key takeaways

• Control Cue Bidding shows 1st (Ace/void) or 2nd (King/singleton) round controls in unbid suits.
• Requires an explicitly agreed trump fit before cue bidding begins.
• Bids progress up the line in cheap order to conserve bidding space.
• Prevents jumping into slams that contain two fast losers in an unbid suit.