SIGNATURE Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. Dated: July 2, 2026 NEXTDECADE CORPORATION By: /s/ Vera de Gyarfas Name: Vera de Gyarfas Title: General Counsel

Entry into a Material Definitive Agreement. On July 2, 2026, Rio Grande LNG, LLC, a Texas limited liability company (“ RGLNG ”) and an indirect subsidiary of NextDecade Corporation (“ NextDecade ” or the “ Company ”), completed its previously announced offering of $1,000 million aggregate principal amount of 5.250% Senior Secured Notes due 2031 (the “ 2031 Notes ”), $500 million aggregate principal amount of 5.500% Senior Secured Notes due 2034 (the “ 2034 Notes ”), $1,250 million aggregate p…

SIGNATURE Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. Dated: June 18, 2026 NEXTDECADE CORPORATION By: /s/ Vera de Gyarfas Name: Vera de Gyarfas Title: General Counsel

Entry into a Material Definitive Agreement. On June 17, 2026 (the “ Closing Date ”), Rio Grande LNG Intermediate HoldCo Borrower, LLC, a Delaware limited liability company (“ RGLNG HoldCo Borrower ”) and an indirect subsidiary of NextDecade Corporation (“ NextDecade ” or the “ Company ”) entered into a Credit Agreement (the “ Credit Agreement ”) by and among RGLNG HoldCo Borrower, as borrower, Wilmington Trust, National Association, as the administrative agent and the collateral agent (the “…

Chief Financial Officer — John Zuklic: The company hired an experienced CFO from another organization.

Chairman of the Board of Directors and Chief Executive Officer — Matthew Schatzman: Amended and restated employment agreement with the CEO, providing more details on compensation and benefits.

Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant. The information included in

The issuance of shares of NEXT common stock underlying the Tranche A/B Warrants, Tranche C Warrants and the Exchange Shares will be made in reliance upon the exemption from registration contained in Section 4(a)(2) of the Securities Act of 1933, as amended, and/or Rule 506 of Regulation D thereunder. SIGNATURE Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. D…

Entry into a Material Definitive Agreement. Amended and Restated Credit Agreement On November 17, 2025 (the “ Closing Date ”), Rio Grande LNG Super Holdings, LLC (“ Super Holdings ”), a wholly-owned indirect subsidiary of NextDecade Corporation (the “ Company ” or “ NEXT ”), entered into an Amended and Restated Credit Agreement (the “ A&R Credit Agreement ”), by and among Super Holdings, as borrower, Atlantic Park Strategic Capital Master Fund II, L.P., as the administrative agent and collate…

Chief Accounting Officer — Luke Boylston: Luke Boylston was promoted to Chief Accounting Officer from his interim role.

Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant. The information included in the sections labeled “RG5 Financing Documents” and “FinCo and Super FinCo Facilities” in

Entry into a Material Definitive Agreement. RG5 Financing Documents On October 16, 2025 (the “FID Date”), Rio Grande LNG Train 5, LLC, a Delaware limited liability company (“RG5”) and an indirect subsidiary of NextDecade Corporation (“NextDecade” or the “Company”), entered into the T5 Common Terms Agreement, the T5 Equity Contribution Agreement, the T5 Collateral and Intercreditor Agreement, the T5 Credit Agreement, the Indenture and the Note Purchase Agreement, each as further described belo…

Chief Financial Officer — Brent Wahl: Mr. Wahl resigned to pursue a professional opportunity in the digital infrastructure industry.

Entry into a Material Definitive Agreement. RG4 Financing Documents On September 9, 2025 (the “FID Date”), Rio Grande LNG Train 4, LLC, a Delaware limited liability company (“RG4”) and an indirect subsidiary of NextDecade Corporation (“NextDecade” or the “Company”), entered into the T4 Common Terms Agreement, the T4 Equity Contribution Agreement, the T4 Collateral and Intercreditor Agreement and the T4 Credit Agreement, each as further described below (each, as defined below, and collectively…

Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant. The information included in the sections labeled “RG4 Financing Documents” and “FinCo and Super FinCo Facilities” in

Other Events. Corporate Credit Agreement Rio Grande LNG Super Holdings, LLC (“Super Holdings”), a wholly-owned subsidiary of the Company and the direct parent of the SF Phase 1 Pledgor, previously entered into a credit agreement (the “Corporate Credit Agreement”) that provides for a $225 million senior secured loan. The Corporate Credit Agreement permits subsidiaries of Super Holdings to incur indebtedness to fund project-level equity in support of the construction of the fourth and fifth liq…

Director — Pamela Beall, In Kyu Park, Diana Sands: The Board of Directors approved increasing the size of the Board and appointed three new directors.

Director — Mr. Timothy Wyatt: Resigned from the Board due to leaving his employment with Hanwha Group to pursue other opportunities.

Entry into a Material Definitive Agreement. Amended and Restated Train 4 EPC Agreement On June 7, 2025, Rio Grande LNG Train 4, LLC (“ RG4 ”), a subsidiary of NextDecade Corporation (the “ Company ”), completed the process to refresh the contract price under its lump sum turnkey engineering, procurement and construction (“ EPC ”) agreement with Bechtel Energy, Inc. (“ Bechtel ”), dated as of August 5, 2024, for the construction of the fourth liquefaction train of the Rio Grande LNG liquefacti…

The excerpt is incomplete and does not provide sufficient information to determine the nature of the event.

SIGNATURE Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. Dated: May 15, 2025 NEXTDECADE CORPORATION By: /s/ Vera de Gyarfas Name: Vera de Gyarfas Title: General Counsel

Entry into a Material Definitive Agreement. Credit Agreement Amendment On May 14, 2025 (the “ Subsequent Closing Date ”), Rio Grande LNG Super Holdings, LLC, a Delaware limited liability company (“ Super Holdings ”) and an indirect subsidiary of NextDecade Corporation (the “ Company ” or “ NEXT ”), entered into an amendment (the “ Amendment ”) to the Credit Agreement (the “ Credit Agreement ”), by and among Super Holdings, as borrower, Atlantic Park Strategic Capital Master Fund II, L.P., as…

principal accounting officer — Eric Garcia: Eric Garcia's departure as the principal accounting officer is a significant loss for the company.

Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant. The information included in

Unregistered Sales of Equity Securities. The information included in