Practice on Cuebids
Practice slam decisions after a fit is found, including when ace asking is useful and when it is premature.
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Systems
Last updated
2026-07-31
What is RKCB?
Roman Key Card Blackwood asks for five key cards: the four aces and the king of trumps. It gives better slam information than classic ace-count Blackwood once a trump suit is agreed.
The two common response structures are 1430 and 3014. The names describe whether the first step shows one or four key cards, or zero or three key cards.
Key-card ask after a major fit
- With hearts agreed, 4NT asks for key cards for hearts.
- The heart king counts as a key card.
1430 versus 3014
In 1430, the cheapest response shows one or four key cards and the next response shows zero or three. In 3014, the first two steps are reversed.
Neither version is right by itself. The important part is that both players remember the same structure.
- 1430: 5 shows one or four; 5 shows zero or three.
- 3014: 5 shows zero or three; 5 shows one or four.
- In either version, 5 shows two or five without the trump queen.
- In either version, 5 shows two or five with the trump queen.
- Many pairs add void-showing replies, such as 5NT with an even number of key cards and a void; the details vary by agreement.
Queen ask
After a 5 or 5 key-card response, the cheapest available bid that is not the agreed trump suit commonly asks for the trump queen. If the next step is the trump suit, the asker skips that bid and uses the next non-trump step.
A common answer structure returns to the agreed trump suit without the queen, bids 5NT with the queen but no side-suit king, and bids a non-trump suit with the queen plus the king of that suit. Partnerships should record any different king-showing treatment. With clear extra trump length, many players answer as if they held the queen, since a combined ten-card fit will usually drop it.
Do not confuse responder's 5NT answer to a queen ask with the asker's later 5NT call. Once the partnership has confirmed all five key cards and the trump queen, the asker can commonly bid 5NT to ask for specific side-suit kings and signal interest in a grand slam. The reply structure must be agreed before using it.
Choosing the asking moment
RKCB works best after the trump suit is clearly agreed and side-suit controls have already been considered. If a side suit may be missing both the ace and king, key-card answers do not protect against two immediate losers.
The asker also needs enough room to stop safely after a bad answer. A 4NT ask that forces the partnership above five of the trump suit can make a manageable game into an unsafe slam try.
After the reply, a return to five of the agreed trump suit is a signoff that partner is expected to pass. When a minor suit is trumps, the answers can force the partnership past five of the suit, so many pairs switch to lower asks such as Kickback or Minorwood in those auctions. Interference over 4NT also needs an agreement; many pairs use DOPI or DEPO to keep the answers playable.
- Use control bidding before RKCB when side suits are uncertain.
- Know whether the trump queen ask is the next step or a special bid.
- Agree how to show specific kings or side-suit features after confirming all key cards.
RKCB examples
The meaning of each response depends on whether the partnership plays 1430 or 3014. The auction examples below focus on the decision logic rather than one mandatory response table.
1430: one or four key cards
- In 1430, 5 shows one or four key cards.
- The asker must know from their own hand whether one or four is possible.
3014: zero or three key cards
- In 3014, 5 shows zero or three key cards.
- The same call means something different here than it does in 1430.
Signing off after a bad answer
- Playing 1430, 5 shows zero or three key cards; an asker holding three key cards knows the answer is zero.
- Missing two key cards, the asker signs off in five of the trump suit, and responder passes.
Queen ask after a safe answer
- With spades agreed, 5 is the cheapest available non-trump step and asks for the spade queen.
- A 5 reply would deny the queen in the common response structure.
Key-card hand evaluation
RKCB can make a slam look scientific, but the asker still has to evaluate shape, controls, and trump quality. Five key cards do not automatically mean thirteen tricks, and missing one key card does not automatically make slam bad.
Good key-card ask shape
- The spade suit is sufficiently strong that key cards may settle the slam decision.
- Side controls are strong, so the ace ask answers a useful question.
Control-bid first shape
- The diamond suit may have quick losers.
- Control bidding before RKCB can prevent a bad slam opposite the wrong hand.
Common mistakes
- Counting only aces and forgetting the trump king.
- Forgetting whether the partnership plays 1430 or 3014.
- Using RKCB before the trump suit is clear.
- Bidding 5NT as a grand-slam try while a key card is still missing.
FAQ
What are the five key cards?
The four aces plus the king of the agreed trump suit.
Is 1430 better than 3014?
Both are playable. Consistency is more important than the chosen structure.
Can I use RKCB when a minor suit is trumps?
Yes, but the answers can force the partnership past five of the minor. Many pairs prefer a lower ask such as Kickback or Minorwood in those auctions.