Kickback is a Blackwood variety consisting of bidding 4♦-4NT directly above the explicitly agreed or the alleged trump.

The alleged trump are:

• • • the suit of the responder, 

    • own suit.

3 versions are used:

• Kickback 0123 (regular):

• step 1 - 0 or 4 aces;

• step 2 - 1 or 5 aces;

• step 3 - 2 aces;

• step 4 - 3 aces.

• Kickback 0314 (Roman Key Card):

  • • step 1 - 0 or 3 aces;

    • step 2 - 1 or 4 aces;

    • step 3 - 2 aces;

    • step 4 - 2 aces + queen.

• Kickback 1430 (Roman Key Card):

  • • step 1 - 0 or 3 aces;

    • step 2 - 1 or 4 aces;

    • step 3 - 2 aces;

    • step 4 - 2 aces + queen.

Exclusions:

• one of the partners showed the length in the strain of the potential bid;

• quantitative 4NT situation and trumps are spades;

• the partner bid unusual 2NT;

• after opening precision 2 ♣ another question about the shape was asked.