Amendment to Quarterly Report (Form 10-Q/A)

BlackRock Monticello Debt Real Estate Investment Trust (the "Company") is filing this Amendment No. 1 (this "Amendment") to its Quarterly Report on Form 10-Q for the period ended March 31, 2026, which was filed with the Securities and Exchange Commission on May 6, 2026 (the "Form for the sole purpose of providing disclosure pursuant to Section 219 of the Iran Threat Reduction and Syria Human Rights Act of 2012 and Section 13(r) of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), as Exhibit 99.1, inadvertently omitted from the Form

In addition, as required by of the Exchange Act, new certifications by the Company's principal executive officer and principal financial officer are filed herewith as exhibits to this Amendment, under Item 6 hereof, pursuant to of the Exchange Act. Because no financial statements have been included in this Amendment and this Amendment does not contain or amend any disclosure with respect to Items paragraphs 3, 4 and 5 of the certifications have been omitted. The Company is also not including new certifications under Section 1350 of Chapter 63 of Title 18 of the United States Code (18 U.S.C. 1350) (Section 906 of the Sarbanes-Oxley Act of 2002), as no financial statements are being filed with this Amendment.

Except as described above, this Amendment does not modify or update disclosure in, or exhibits to, the Form Furthermore, this Amendment does not change any previously reported financial results, nor does it reflect events occurring after the filing date of the Form This Amendment should be read in conjunction with the Form 10-Q.