https://web2.acbl.org/documentLibrary/play/AlertProcedures2.pdf
ACBL Rule Changes summarized*
The ACBL Board of Directors unanimously approved a comprehensive update to the ACBL Alert Procedure which went into effect Jan 1st, 2021. The full document is available here.
Pre-Alerts
The first changes are at the beginning of the round. As before, you must pre-Alert the opponents if you play canape methods or different systems depending on seat or vulnerability (but not just because you play different ranges for opening 1NT). Additionally you now are required to pre-Alert if you play a system that includes at least one one-level opening bid that is not natural or that is forcing. This can be as simple as saying, “We play a strong club” or “We play 1♣ could be short.” You are no longer required to pre-Alert if you lead low from small doubletons. However, if you play this, it must be included in your answer when a declarer asks about your leads and carding.
Alert changes
The new Alert procedure starts from the principle that natural calls are not Alerted, and that artificial calls are Alerted. It then gives the deviations from that principle, spelling out the natural calls that must be Alerted (for example, a response to a one-level opening bid that is not forcing), and the artificial calls that do not require Alerts (for example, Stayman). The most common calls that have had their Alertability changed are as follows:
- In an uncontested auction, no natural jumpshift (whether weak, intermediate or strong) requires an Alert.
- A direct cuebid that is not Michaels (showing both majors over a minor, or a major and an unspecified minor over a major) requires an Alert.
- Support doubles and redoubles no longer require an Alert.
- An opening 2♣ bid that does not meet the definition of Very Strong requires an Alert. (This tends to apply to partnerships who agree to open 2♣ on hands with good playing strength, but many fewer high cards than normal. See the Convention Chart for the exact definition to see if it applies to you.)
Announcement changes
There were also a few changes to Announcements, with the biggest change for transfers. Instead of saying the word “transfer,” the Announcement is now the name of the suit being transferred to. For example, in the auction 1NT–2♥, where partner’s 2♥ showed spades, instead of Announcing “transfer,” you will now Announce “spades.”
This Announcement is used in any situation where your partner is showing length in a specific other suit, as well as for doubles or redoubles that show the next suit up. For example, if you play that 2♠ shows clubs in the auction 1NT–2♠, then you would announce “clubs.” However, if you play that 2♠ shows either minor in the auction 1NT–2♠, then you must say “Alert,” even if the 1NT opener is expected to always bid clubs.
An example of the rule for doubles is if you play that after a 1♣ opening is overcalled with 1♦, that a double shows hearts (and says nothing about spades as a traditional negative double would), then you would announce “hearts” when your partner doubled. Traditional negative doubles are never Alerted or Announced.
Instead of saying “could be short” for a non-forcing minor-suit opening that might contain fewer than three cards, you must say the minimum number of cards in the suit, as in “Could be one.”
If you have the agreement to routinely bypass a four-card spade suit to bid a forcing or semi-forcing 1NT over 1♥, then you add “could have four spades” to the “forcing” or “semiforcing” Announcement. This is most likely applicable to pairs playing Flannery.
Delayed Alerts
The rules for delayed Alerts have slightly changed, with the main difference being that at the end of the auction, the declaring side should explain any delayed Alerts and point out any control bids that were made during the auction without a requirement for the defense to ask about them. By having the declaring side explain these calls without prompting, there should be fewer cases of the person not on lead asking about calls before they should.
*Summary taken from BBO