Material Event (Form 8-K)

On March 12, 2026, Northern States Power Company, a Minnesota corporation ("NSP-Minnesota"),issued $600 million in aggregate principal amount of 4.85% First Mortgage Bonds, Series due May 15, 2036 and $600 million in aggregate principal amount of 5.55% First Mortgage Bonds, Series due May 15, 2056 (collectively, the "bonds") pursuant to an Underwriting Agreement among NSP-Minnesotaand BNP Paribas Securities Corp., KeyBanc Capital Markets Inc., PNC Capital Markets LLC, SMBC Nikko Securities America, Inc. and U.S. Bancorp Investments, Inc., as representatives of the underwriters named therein. The bonds are being issued pursuant to the registration statement on Form S-3(File No. 333-278797-04)(the "Registration Statement"). A prospectus supplement relating to the offering and sale of the bonds was filed with the Securities and Exchange Commission on March 6, 2026. The bonds will be governed by NSP-Minnesota'sSupplemental and Restated Trust Indenture dated May 1, 1988, by and between NSP-Minnesotaand The Bank of New York Mellon Trust Company, N.A., as successor trustee, and the Supplemental Trust Indenture dated as of February 1, 2026.

This Current Report on Form 8-Kis being filed to report as exhibits certain documents in connection with that offering and sale for incorporation by reference into the Registration Statement.