ACABW Atlantic Coastal Acquisition Corporation II

Exhibit 3.1

AMENDMENT NO. 3 TO THE AMENDED AND RESTATED CERTIFICATE OF INCORPORATION OF

ATLANTIC COASTAL ACQUISITION CORP. II

Pursuant to Section 242 of the

Delaware General Corporation Law

ATLANTIC COASTAL ACQUISITION CORP. II (the “Corporation”), a corporation organized and existing under the laws of the State of Delaware, does hereby certify as follows:

“Immediately after the Offering, a certain amount of the net offering proceeds received by the Corporation in the Offering (including the proceeds of any exercise of the underwriters’ over-allotment option) and certain other amounts specified in the Corporation’s registration statement on Form S-1, initially filed with the U.S. Securities and Exchange Commission (the “SEC”) on December 2, 2021, as amended (the “Registration Statement”), shall be deposited in a trust account (the “Trust Account”), established for the benefit of the Public Stockholders (as defined below) pursuant to a trust agreement described in the Registration Statement. Except for the withdrawal of interest to pay taxes, none of the funds held in the Trust Account (including the interest earned on the funds held in the Trust Account) will be released from the Trust Account until the earliest to occur of (i) the completion of the initial Business Combination, (ii) the redemption of 100% of the Offering Shares (as defined below) not previously properly redeemed in accordance with clause (iii) below if the Corporation is unable to complete its initial Business Combination by October 19, 2024 (the “Termination Date”) (or up to November 19, 2024, if applicable in accordance with this Section 9.1(b)) or such earlier date as determined by the Board and (iii) the redemption of shares in connection with a vote seeking to amend such provisions of this Certificate as described in Section 9.7 hereof. Holders of shares of Common Stock included as part of the units sold in the Offering (the “Offering Shares”) (whether such Offering Shares were purchased in the Offering or in the secondary market following the Offering and whether or not such holders are the Sponsor or officers or directors of the Corporation, or affiliates of any of the foregoing) are referred to herein as “Public Stockholders.” In the event that the Corporation has not consummated an initial Business Combination by the Termination Date, the Board may, without another stockholder vote, elect to extend the period of time to consummate a Business Combination once after October 19, 2024, by resolution of the Board if requested by Atlantic Coastal Acquisition Management II

LLC (the “Sponsor”), and upon five days’ advance notice prior to the Extended Date, until November 19, 2024, provided that the Sponsor (or one or more of its affiliates or permitted designees) (the “Payor”) will deposit into the Trust Account $0.03 for each then-outstanding Offering Share for such monthly extension.

“In the event that the Corporation has not consummated an initial Business Combination by the Termination Date (or up to November 19, 2024, if applicable in accordance with Section 9.1(b) above) or such earlier date as determined by the Board, the Corporation shall (i) cease all operations except for the purpose of winding up, (ii) as promptly as reasonably possible but not more than ten (10) business days thereafter subject to lawfully available funds therefor, redeem 100% of the Offering Shares in consideration of a per-share price, payable in cash, equal to the quotient obtained by dividing (A) the aggregate amount then on deposit in the Trust Account, including interest not previously released to the Corporation to pay its taxes (less up to $100,000 of interest to pay dissolution expenses), by (B) the total number of then outstanding Offering Shares, which redemption will completely extinguish rights of the Public Stockholders (including the right to receive further liquidating distributions, if any), subject to applicable law, and (iii) as promptly as reasonably possible following such redemption, subject to the approval of the remaining stockholders and the Board in accordance with applicable law, dissolve and liquidate, subject in each case to the Corporation’s obligations under the DGCL to provide for claims of creditors and other requirements of applicable law.”

“Additional Redemption Rights. If, in accordance with Section 9.1(a) hereof, any amendment is made to this Certificate (a) to modify the substance or timing of the Corporation’s obligation to redeem 100% of the Offering Shares if the Corporation has not consummated an initial Business Combination by Termination Date (or up to November 19, 2024, if applicable in accordance with Section 9.1(b) above) or such earlier date as determined by the Board or (b) with respect to any other material provisions of this Certificate relating to stockholders’ rights or pre-initial Business Combination activity, the Public Stockholders shall be provided with the opportunity to redeem their Offering Shares upon the approval of any such amendment, at a per-share price, payable in cash, equal to the aggregate amount then on deposit in the Trust Account, including interest not previously released to the Corporation to pay its taxes, divided by the number of then outstanding Offering Shares; provided, however, that any such amendment will be voided, and this Article IX will remain unchanged, if any stockholders who wish to redeem are unable to redeem due to the Redemption Limitation.”

IN WITNESS WHEREOF, Atlantic Coastal Acquisition Corp. II has caused this Amendment No. 3 to the Amended and Restated Certificate to be duly executed in its name and on its behalf by an authorized officer as of this day of September 19, 2024.

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