Organization	12 Months Ended
Dec. 31, 2025
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	1. ORGANIZATION Phillip Street Middle Market Lending Fund LLC (the “Company”) is a Delaware limited liability company formed on July 13, 2022. The Company has elected to be regulated as a business development company (“BDC”) under the Investment Company Act of 1940, as amended (the “Investment Company Act”). In addition, the Company has elected to be treated as a regulated investment company (“RIC”), and the Company expects to qualify annually for tax treatment as a RIC under Subchapter M of the Internal Revenue Code of 1986, as amended (the “Code”), commencing with its taxable year ended December 31, 2022. The Company commenced operations on October 6, 2022. On November 2, 2022, the Company's initial investors (other than the Initial Member (as defined below)) funded the initial portion of their capital commitment to purchase units of the Company’s limited liability interest (“Units”). The Company’s investment objective is to generate current income and, to a lesser extent, capital appreciation primarily through direct originations of secured debt, including first lien, unitranche debt, including last out portions of such loans, and second lien debt, and unsecured debt, including mezzanine debt, as well as through select equity investments. Goldman Sachs Asset Management, L.P. (“GSAM”), a Delaware limited partnership and an affiliate of Goldman Sachs & Co. LLC (including its predecessors, “GS & Co.”), is the investment adviser (the “Investment Adviser”) of the Company. The term “Goldman Sachs” refers to The Goldman Sachs Group, Inc. (“GS Group Inc.”), together with GS & Co., GSAM and its other subsidiaries. The Company is conducting an offering pursuant to which investors will make a capital commitment (a “Commitment”) to purchase Units pursuant to a subscription agreement entered into with the Company pursuant to which the investor will agree to purchase Units for an aggregate purchase price equal to its Commitment. Each investor will be required to purchase the Company’s Units each time the Company delivers a drawdown notice at least 10 business days prior to the required funding date (the “Drawdown Date”). The offering and sale of Units will be exempt from registration pursuant to Regulation D and Regulation S promulgated under the U.S. Securities Act of 1933, as amended, for offers and sales of securities that do not involve a public offering and for offers and sale of securities outside of the United States. On October 6, 2022, the Company received a capital commitment of $10 from an affiliate of the Investment Adviser (the “Initial Member”). The Initial Member was the sole owner of the Company’s interests until the period beginning on the first date on which investors in the Company are required to make the initial capital contribution to purchase Units, and Units are issued in respect thereof (the “Initial Drawdown Date”). On October 19, 2022, the Company began accepting subscription agreements ("Subscription Agreements") from investors acquiring Units of the Company in the Company's private offering. Under the terms of the Subscription Agreements, investors are required to make capital contributions up to the undrawn amount of their capital commitment to purchase Units each time the Company delivers a drawdown notice. On March 1, 2023, the Company’s board of directors (the “Board of Directors” or the “Board”) approved an amended and restated limited liability company agreement. The Company has formed wholly-owned subsidiaries, which are structured as Delaware limited liability companies, to hold certain equity or equity-like investments in portfolio companies and corporate debt of portfolio companies.

Phillip Street Middle Market Lending Fund LLC (the “Company”) is a Delaware limited liability company formed on July 13, 2022. The Company has elected to be regulated as a business development company (“BDC”) under the Investment Company Act of 1940, as amended (the “Investment Company Act”). In addition, the Company has elected to be treated as a regulated investment company (“RIC”), and the Company expects to qualify annually for tax treatment as a RIC under Subchapter M of the Internal Revenue Code of 1986, as amended (the “Code”), commencing with its taxable year ended December 31, 2022. The Company commenced operations on October 6, 2022. On November 2, 2022, the Company's initial investors (other than the Initial Member (as defined below)) funded the initial portion of their capital commitment to purchase units of the Company’s limited liability interest (“Units”).

The Company’s investment objective is to generate current income and, to a lesser extent, capital appreciation primarily through direct originations of secured debt, including first lien, unitranche debt, including last out portions of such loans, and second lien debt, and unsecured debt, including mezzanine debt, as well as through select equity investments.

Goldman Sachs Asset Management, L.P. (“GSAM”), a Delaware limited partnership and an affiliate of Goldman Sachs & Co. LLC (including its predecessors, “GS & Co.”), is the investment adviser (the “Investment Adviser”) of the Company. The term “Goldman Sachs” refers to The Goldman Sachs Group, Inc. (“GS Group Inc.”), together with GS & Co., GSAM and its other subsidiaries.

The Company is conducting an offering pursuant to which investors will make a capital commitment (a “Commitment”) to purchase Units pursuant to a subscription agreement entered into with the Company pursuant to which the investor will agree to purchase Units for an aggregate purchase price equal to its Commitment. Each investor will be required to purchase the Company’s Units each time the Company delivers a drawdown notice at least 10 business days prior to the required funding date (the “Drawdown Date”). The offering and sale of Units will be exempt from registration pursuant to Regulation D and Regulation S promulgated under the U.S. Securities Act of 1933, as amended, for offers and sales of securities that do not involve a public offering and for offers and sale of securities outside of the United States.

On October 6, 2022, the Company received a capital commitment of $10 from an affiliate of the Investment Adviser (the “Initial Member”). The Initial Member was the sole owner of the Company’s interests until the period beginning on the first date on which investors in the Company are required to make the initial capital contribution to purchase Units, and Units are issued in respect thereof (the “Initial Drawdown Date”).

On October 19, 2022, the Company began accepting subscription agreements ("Subscription Agreements") from investors acquiring Units of the Company in the Company's private offering. Under the terms of the Subscription Agreements, investors are required to make capital contributions up to the undrawn amount of their capital commitment to purchase Units each time the Company delivers a drawdown notice. On March 1, 2023, the Company’s board of directors (the “Board of Directors” or the “Board”) approved an amended and restated limited liability company agreement.

The Company has formed wholly-owned subsidiaries, which are structured as Delaware limited liability companies, to hold certain equity or equity-like investments in portfolio companies and corporate debt of portfolio companies.