UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D/A

Under the Securities Exchange Act of 1934
(Amendment No. 10)*

NMF SLF I, INC.

(Name of Issuer)

Common Stock, $0.001 par value per share

(Title of Class of Securities)

None

(CUSIP Number)

(Name, Address and Telephone Number of Person
Authorized to Receive Notices and Communications)

January 20, 2023

(Date of Event which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box. o

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See §240.13d-7 for other parties to whom copies are to be sent.

^* The remainder of this cover page shall be filled out for a reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

Item 1.  Security and Issuer.

This Amendment No. 10 (“Amendment No. 10”) amends the statement on Schedule 13D filed with the Securities and Exchange Commission on February 21, 2020, as amended by Amendment No. 1 on March 30, 2020, Amendment No. 2 on May 4, 2020, Amendment No. 3 on August 27, 2020, Amendment No. 4 on December 10, 2020, Amendment No. 5 on July 20, 2021, Amendment No. 6 on August 30, 2021, Amendment No. 7 on December 15, 2021, Amendment No. 8 on January 19, 2022, and Amendment No. 9 on August 1, 2022. This Amendment No. 10 relates to shares of common stock (the “Shares”) of NMF SLF I, Inc., a Maryland business development company (the “Issuer”). The Issuer’s principal executive offices are located at 787 Seventh Avenue, 48^th Floor, New York, NY 10019.

Item 4.  Purpose of Transaction.

On January 27, 2020, each Plan entered into a subscription agreement with the Issuer (the “Subscription Agreements”) pursuant to which the UAW Chrysler Retirees Medical Benefits Plan agreed to purchase Shares for an aggregate purchase price equal to $104,000,000, the UAW Ford Retirees Medical Benefits Plan agreed to purchase Shares for an aggregate purchase price equal to $163,000,000, and the UAW GM Retirees Medical Benefits Plan agreed to purchase Shares for an aggregate purchase price equal to $233,000,000. Such amounts are payable at such times and in such amounts as required by the Issuer, under the terms and conditions set forth in the Subscription Agreements.

On February 3, 2020, pursuant to drawdown notices delivered in accordance with the Subscription Agreements: (i) UAW Chrysler Retirees Medical Benefits Plan purchased from the Issuer, and the Issuer issued to UAW Chrysler Retirees Medical Benefits Plan, 1,040,000 Shares; (ii) UAW Ford Retirees Medical Benefits Plan purchased from the Issuer, and the Issuer issued to UAW Ford Retirees Medical Benefits Plan, 1,630,000 Shares; and (iii) UAW GM Retirees Medical Benefits Plan purchased from the Issuer, and the Issuer issued to UAW GM Retirees Medical Benefits Plan, 2,330,000 Shares..

On March 26, 2020, pursuant to drawdown notices delivered in accordance with the Subscription Agreements: (i) UAW Chrysler Retirees Medical Benefits Plan purchased from the Issuer, and the Issuer issued to UAW Chrysler Retirees Medical Benefits Plan, 1,040,000 Shares; (ii) UAW Ford Retirees Medical Benefits Plan purchased from the Issuer, and the Issuer issued to UAW Ford Retirees Medical Benefits Plan, 1,630,000 Shares; and (iii) UAW GM Retirees Medical Benefits Plan purchased from the Issuer, and the Issuer issued to UAW GM Retirees Medical Benefits Plan, 2,330,000 Shares.

On May 4, 2020, pursuant to drawdown notices delivered in accordance with the Subscription Agreements: (i) UAW Chrysler Retirees Medical Benefits Plan purchased from the Issuer, and the Issuer issued to UAW Chrysler Retirees Medical Benefits Plan, 2,080,000 Shares; (ii) UAW Ford Retirees Medical Benefits Plan purchased from the Issuer, and the Issuer issued to UAW Ford Retirees Medical Benefits Plan, 3,260,000 Shares; and (iii) UAW GM Retirees Medical Benefits Plan purchased from the Issuer, and the Issuer issued to UAW GM Retirees Medical Benefits Plan, 4,660,000 Shares.

On August 27, 2020, pursuant to drawdown notices delivered in accordance with the Subscription Agreements: (i) UAW Chrysler Retirees Medical Benefits Plan purchased from the Issuer, and the Issuer issued to UAW Chrysler Retirees Medical Benefits Plan, 1,474,480 Shares; (ii) UAW Ford Retirees Medical Benefits Plan purchased from the Issuer, and the Issuer issued to UAW Ford Retirees Medical Benefits Plan, 2,310,964 Shares; and (iii) UAW GM Retirees Medical Benefits Plan purchased from the Issuer, and the Issuer issued to UAW GM Retirees Medical Benefits Plan, 3,303,403 Shares.

On November 19, 2020, each Plan entered into a commitment update with the Issuer pursuant to which the UAW Chrysler Retirees Medical Benefits Plan increased its aggregate capital commitment to purchase Shares from $104,000,000 to $137,800,000, the UAW Ford Retirees Medical Benefits Plan increased its aggregate capital commitment to purchase Shares from $163,000,000 to $213,850,000, and the UAW GM Retirees Medical Benefits Plan increased its aggregate capital commitment to purchase Shares from $233,000,000 to $298,350,000. Such amounts are payable at such times and in such amounts as required by the Issuer, under the terms and conditions set forth in the Subscription Agreements.

On December 10, 2020, pursuant to drawdown notices delivered in accordance with the Subscription Agreements: (i) UAW Chrysler Retirees Medical Benefits Plan purchased from the Issuer, and the Issuer issued to UAW Chrysler Retirees Medical Benefits Plan, 1,482,584 Shares; (ii) UAW Ford Retirees Medical Benefits Plan purchased from the Issuer, and the Issuer issued to UAW Ford Retirees Medical Benefits Plan, 2,218,211 Shares; and (iii) UAW GM Retirees Medical Benefits Plan purchased from the Issuer, and the Issuer issued to UAW GM Retirees Medical Benefits Plan, 2,806,695 Shares.

On April 13, 2021, pursuant to a distribution reinvestment plan (i) UAW Chrysler Retirees Medical Benefits Plan reinvested distribution proceeds in the Issuer and the Issuer issued to UAW Chrysler Retirees Medical Benefits Plan 167,726.57 Shares; (ii) UAW Ford Retirees Medical Benefits Plan reinvested distribution proceeds in the Issuer and the Issuer issued to UAW Ford Retirees Medical Benefits Plan 260,393.92 Shares; and (iii) UAW GM Retirees Medical Benefits Plan reinvested distribution proceeds in the Issuer and the Issuer issued to UAW GM Retirees Medical Benefits Plan 363,638.35 Shares.

On July 13, 2021, pursuant to distribution reinvestment plans (i) UAW Chrysler Retirees Medical Benefits Plan reinvested distribution proceeds in the Issuer and the Issuer issued to UAW Chrysler Retirees Medical Benefits Plan 197,548 Shares; (ii) UAW Ford Retirees Medical Benefits Plan reinvested distribution proceeds in the Issuer and the Issuer issued to UAW Ford Retirees Medical Benefits Plan 306,691 Shares; and (iii) UAW GM Retirees Medical Benefits Plan reinvested distribution proceeds in the Issuer and the Issuer issued to UAW GM Retirees Medical Benefits Plan 428,292 Shares.

On August 30, 2021, pursuant to drawdown notices delivered in accordance with the Subscription Agreements: (i) UAW Chrysler Retirees Medical Benefits Plan purchased from the Issuer, and the Issuer issued to UAW Chrysler Retirees Medical Benefits Plan, 2,814,856,.08 Shares; (ii) UAW Ford Retirees Medical Benefits Plan purchased from the Issuer, and the Issuer issued to UAW Ford Retirees Medical Benefits Plan, 4,368,337.98 Shares; and (iii) UAW GM Retirees Medical Benefits Plan purchased from the Issuer, and the Issuer issued to UAW GM Retirees Medical Benefits Plan, 6,094,428.97 Shares.

On December 15, 2021, pursuant to drawdown notices delivered in accordance with the Subscription Agreements: (i) UAW Chrysler Retirees Medical Benefits Plan purchased from the Issuer, and the Issuer issued to UAW Chrysler Retirees Medical Benefits Plan, 3,228,678.54 Shares; (ii) UAW Ford Retirees Medical Benefits Plan purchased from the Issuer, and the Issuer issued to UAW Ford Retirees Medical Benefits Plan, 5,010,543.58 Shares; and (iii) UAW GM Retirees Medical Benefits Plan purchased from the Issuer, and the Issuer issued to UAW GM Retirees Medical Benefits Plan, 6,990,393.63 Shares.

On January 13, 2022, pursuant to distribution reinvestment plans (i) UAW Chrysler Retirees Medical Benefits Plan reinvested distribution proceeds in the Issuer and the Issuer issued to UAW Chrysler Retirees Medical Benefits Plan 596,656 Shares; (ii) UAW Ford Retirees Medical Benefits Plan reinvested distribution proceeds in the Issuer and the Issuer issued to UAW Ford Retirees Medical Benefits Plan 926,172 Shares; and (iii) UAW GM Retirees Medical Benefits Plan reinvested distribution proceeds in the Issuer and the Issuer issued to UAW GM Retirees Medical Benefits Plan 1,292,930 Shares.

On July 20, 2022, pursuant to distribution reinvestment plans (relating to distributions with record dates of March 30, 2022) (i) UAW Chrysler Retirees Medical Benefits Plan reinvested distribution proceeds in the Issuer and the Issuer issued to UAW Chrysler Retirees Medical Benefits Plan 292,282 Shares; (ii) UAW Ford Retirees Medical Benefits Plan reinvested distribution proceeds in the Issuer and the Issuer issued to UAW Ford Retirees Medical Benefits Plan 453,687 Shares; and (iii) UAW GM Retirees Medical Benefits Plan reinvested distribution proceeds in the Issuer and the Issuer issued to UAW GM Retirees Medical Benefits Plan 633,297 Shares.

On July 20, 2022, pursuant to distribution reinvestment plans (relating to distributions with record dates of June 29, 2022) (i) UAW Chrysler Retirees Medical Benefits Plan reinvested distribution proceeds in the Issuer and the Issuer issued to UAW Chrysler Retirees Medical Benefits Plan 311,201 Shares; (ii) UAW Ford Retirees Medical Benefits Plan reinvested distribution proceeds in the Issuer and the Issuer issued to UAW Ford Retirees Medical Benefits Plan 483,054 Shares; and (iii) UAW GM Retirees Medical Benefits Plan reinvested distribution proceeds in the Issuer and the Issuer issued to UAW GM Retirees Medical Benefits Plan 674,291 Shares.

On January 20, 2023, pursuant to distribution reinvestment plans (relating to distributions with record dates of September 29, 2022) (i) UAW Chrysler Retirees Medical Benefits Plan reinvested distribution proceeds in the Issuer and the Issuer issued to UAW Chrysler Retirees Medical Benefits Plan 355,504 Shares; (ii) UAW Ford Retirees Medical Benefits Plan reinvested distribution proceeds in the Issuer and the Issuer issued to UAW Ford Retirees Medical Benefits Plan 551,821 Shares; and (iii) UAW GM Retirees Medical Benefits Plan reinvested distribution proceeds in the Issuer and the Issuer issued to UAW GM Retirees Medical Benefits Plan 770,283 Shares.

On January 20, 2023, pursuant to distribution reinvestment plans (relating to distributions with record dates of December 30, 2022) (i) UAW Chrysler Retirees Medical Benefits Plan reinvested distribution proceeds in the Issuer and the Issuer issued to UAW Chrysler Retirees Medical Benefits Plan 419,933 Shares; (ii) UAW Ford Retirees Medical Benefits Plan reinvested distribution proceeds in the Issuer and the Issuer issued to UAW Ford Retirees Medical Benefits Plan 651,829 Shares; and (iii) UAW GM Retirees Medical Benefits Plan reinvested distribution proceeds in the Issuer and the Issuer issued to UAW GM Retirees Medical Benefits Plan 909,883 Shares.

The purpose of each transaction was to acquire securities of the Issuer for investment purposes.

The Issuer is a business development company. The Reporting Persons expect to continue to beneficially own, in the aggregate, greater than 94% of the Shares outstanding. The investment strategy and investment policy of the Issuer have been devised by, and will be implemented by, New Mountain Finance Advisers BDC, L.L.C. The Reporting Persons do not have any plans or proposals to make any changes to the Issuer’s investment policy.

The Reporting Persons may change their intention with respect to any and all matters referred to in this Item 4.

Except as set forth herein, the Reporting Persons have no present plan or proposal that would relate to or result in any of the matters set forth in subparagraphs (a)-(j) of Item 4 of Schedule 13D.

Item 5.  Interest in Securities of the Issuer.

(a) The aggregate number of Shares to which this Amendment No. 10 relates is 73,150,690. Such aggregate number of Shares represents 94.2% of the common stock of the Issuer. The percentage reported in this Amendment No. 10 is calculated based upon 77,633,532 Shares stated to be outstanding as of January 20, 2023 as indicated by the Issuer.

(b) The UAW Chrysler Retirees Medical Benefits Plan beneficially owns and has shared voting and dispositive power of 15,501,450 Shares. Such Shares represent 20.0% of the Shares outstanding.

The UAW Ford Retirees Medical Benefits Plan beneficially owns and has shared voting and dispositive power of 24,061,704 Shares. Such Shares represent 31.0% of the Shares outstanding.

The UAW GM Retirees Medical Benefits Plan beneficially owns and has shared voting and dispositive power of 33,587,536 Shares. Such Shares represent 43.3% of the Shares outstanding.

UAW RMBT is the trust under which the Plans are established and, pursuant to Rule 13d-3, may be deemed to beneficially own the 73,150,690 Shares held by the Plans. Such Shares represent 94.2% of the Shares outstanding. UAW RMBT is an indirect beneficial owner of these Shares.

Hershel Harper is the chief investment officer of UAW RMBT, the trust under which the Plans are established, and, pursuant to Rule 13d-3 may be deemed to beneficially own the 73,150,690 Shares held by the Plans. Such Shares represent 94.2% of the Shares outstanding. Hershel Harper is an indirect beneficial owner of these Shares.

(c) Except as disclosed in Item 4, no transactions in the Shares were effected during the past sixty days by the Reporting Persons.

(d) Not applicable.

(e) Not applicable.

Item 6.  Contracts, Arrangements, Understandings or Relationships with Respect to Securities of the Issuer.

On January 27, 2020, each Plan entered into a Subscription Agreement with the Issuer. For more information about the Subscription Agreements and the terms thereof, please refer to Item 4 above and Exhibit 7.1 hereto.

On January 27, 2020, the Plans entered into a letter agreement pursuant to which the Plans requested to receive, and the Issuer agreed to provide, periodic and other information.

Pursuant to Rule 13d-1(k) promulgated under the Securities Exchange Act of 1934, as amended, the Reporting Persons have entered into a Joint Filing Agreement with respect to the joint filing of this statement and any amendments hereto, a copy of which is filed as Exhibit 99.5 hereto.

The foregoing description is qualified in its entirety by reference to the full texts of the referenced agreements, which are filed as exhibits to this Schedule 13D.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Dated: January 27, 2023