Bsb Bancorp Inc.

Bsb Bancorp Inc. – Contract (November 2nd, 2018)

Bsb Bancorp Inc. – Belmont Savings Bank Supplemental Executive Retirement Plan (March 16th, 2018)

Bsb Bancorp Inc. – Contract (March 16th, 2018)

Bsb Bancorp Inc. – SEVERANCE AGREEMENT by and Between BELMONT SAVINGS BANK and CARROLL M. LOWENSTEIN, JR. (November 8th, 2017)

This Severance Agreement (the "Agreement") is made and entered into as of November 3, 2017 (the "Execution Date"), by and between Belmont Savings Bank, a Massachusetts-chartered savings bank with its principal administrative office at Two Leonard Street, Belmont, MA 02478 (together with its successors and assigns, the "Bank") and Carroll M. Lowenstein, Jr. ("Executive").

Bsb Bancorp Inc. – Belmont Savings Bank Supplemental Executive Retirement Plan Appendix A-2 (May 5th, 2017)

Except as otherwise defined in this Appendix, the terms used herein shall have the meaning(s) ascribed to them in the Belmont Savings Bank Supplemental Executive Retirement Plan (Plan), to which this Appendix, as amended from time to time, is appended and into which this Appendix is incorporated by reference.

Bsb Bancorp Inc. – Belmont Savings Bank Supplemental Executive Retirement Plan Appendix A-1 (May 5th, 2017)

Except as otherwise defined in this Appendix, the terms used herein shall have the meaning(s) ascribed to them in the Belmont Savings Bank Supplemental Executive Retirement Plan (Plan), to which this Appendix, as amended from time to time, is appended and into which this Appendix is incorporated by reference.

Bsb Bancorp Inc. – Belmont Savings Bank Supplemental Executive Retirement Plan Appendix A-4 (May 5th, 2017)

Except as otherwise defined in this Appendix, the terms used herein shall have the meaning(s) ascribed to them in the Belmont Savings Bank Supplemental Executive Retirement Plan (Plan), to which this Appendix, as amended from time to time, is appended and into which this Appendix is incorporated by reference.

Bsb Bancorp Inc. – Belmont Savings Bank Supplemental Executive Retirement Plan Appendix A-3 (May 5th, 2017)

Except as otherwise defined in this Appendix, the terms used herein shall have the meaning(s) ascribed to them in the Belmont Savings Bank Supplemental Executive Retirement Plan (Plan), to which this Appendix, as amended from time to time, is appended and into which this Appendix is incorporated by reference.

Bsb Bancorp Inc. – Form of Restricted Stock Agreement (March 20th, 2017)

Bsb Bancorp Inc. – BSB Bancorp, Inc. INCENTIVE COMPENSATION PLAN (March 10th, 2017)

Bsb Bancorp Inc. – First Amendment to Amended and Restated Supplemental Retirement Agreement (December 2nd, 2014)

WHEREAS, Belmont Savings Bank, a Massachusetts savings bank with its principal place of business in Belmont, Massachusetts (the "Bank") and John A. Citrano ("Executive") have entered into an Amended and Restated Supplemental Retirement Agreement, effective February 12, 2014 ("Agreement"), which Agreement superseded and replaced the Restated Supplemental Retirement Agreement between the Bank and the Executive, dated December 23, 2008 ("Prior Agreement"); and

Bsb Bancorp Inc. – Amended and Restated Supplemental Retirement Agreement (February 19th, 2014)

THIS AMENDED AND RESTATED SUPPLEMENTAL RETIREMENT AGREEMENT ("Agreement") is entered into as of February 12, 2014, by and between Belmont Savings Bank, a Massachusetts savings bank with its principal place of business in Belmont, Massachusetts ( "Bank"), and John A. Citrano ( "Executive"):

Bsb Bancorp Inc. – March 23, 2011 BSB Bancorp, MHC Belmont Center Two Leonard Street Belmont, MA 02478 BSB Bancorp Inc. Belmont Center Two Leonard Street Belmont, MA 02478 Belmont Savings Bank Belmont Center Two Leonard Street Belmont, MA 02478 (August 10th, 2011)

This letter confirms the engagement of Keefe, Bruyette & Woods, Inc. (KBW) to act as the financial advisor to BSB Bancorp, MHC (the MHC), BSB Bancorp Inc. (the Bancshares), and Belmont Savings Bank (the Bank) in connection with the proposed conversion and reorganization from the mutual holding company form of organization to a stock holding company form of organization pursuant to a Plan of Conversion and Reorganization to be adopted by the MHC, the Bancshares, and the Bank (the Reorganization). In order to effect the Reorganization, it is contemplated that the MHC will merge into the Bancshares and the Bancshares will merge into a new stock holding company (the Holding Company) and that the Holding Company will offer and sell shares of its common stock (the Common Stock) to eligible persons in a Subscription Offering, with any remaining shares offered to the general public in a Community Offering and if necessary, through a syndicate of broker-dealers organized by KBW (a Syndicated Co

Bsb Bancorp Inc. – Article 7. Stock Purchase Priorities (August 10th, 2011)

This Plan of Conversion (the Plan) provides for the conversion and reorganization of BSB Bancorp, MHC, a Massachusetts-chartered mutual holding company (the MHC), into the capital stock form of organization (the Conversion). The MHC currently owns 100% of the common stock of BSB Bancorp, Inc., a Massachusetts corporation (the Mid-Tier Holding Company), which owns 100% of the common stock of Belmont Savings Bank (the Bank), a Massachusetts-chartered savings bank, which is headquartered in Belmont, Massachusetts. Capitalized terms used but not defined in this Article 1 shall have the respective meanings set forth in Article 2 hereof.

Bsb Bancorp Inc. – Bylaws of Bsb Bancorp, Inc. Effective: June 2, 2011 (July 19th, 2011)

The name of this corporation (hereinafter in these Bylaws called the Corporation) is BSB Bancorp, Inc., or such other name as hereafter may be adopted in accordance with law. The main office of the Corporation is and shall be located in Belmont, Massachusetts, subject to changes as authorized by law. The Corporation may have such additional offices, either within or without the United States, as the Board of Directors may from time to time designate in accordance with applicable law. The Corporation shall have and may exercise all of the powers, privileges and authority, expressed and implied, now or hereafter conferred by applicable law.

Bsb Bancorp Inc. – BELMONT SAVINGS BANK Two Leonard Street Belmont, Massachusetts 02478-2511 DEFERRED COMPENSATION AGREEMENT (June 9th, 2011)

AGREEMENT made and entered into as of this 21st day of December, 2006, by and between Belmont Savings Bank, a Massachusetts savings bank corporation organized under Massachusetts General Laws, Chapter 168, with its principal office and place of business at Two Leonard Street, Belmont, Massachusetts (hereinafter referred to as the Bank) and John A. Borelli, an individual who is currently serving as a Trustee of the Bank (hereinafter referred to as the Trustee).

Bsb Bancorp Inc. – Belmont Savings Bank Capital Appreciation Plan Article 1 Purposes (June 9th, 2011)

Bsb Bancorp Inc. – SEVERANCE AGREEMENT by and Between BELMONT SAVINGS BANK and JOHN A. CITRANO (June 9th, 2011)

This Severance Agreement (the Agreement) is made and entered into as of , 2011 (the Execution Date), by and between Belmont Savings Bank, a Massachusetts-chartered savings bank with its principal administrative office at Two Leonard Street, Belmont, MA 02478 (together with its successors and assigns, the Bank) and John A. Citrano (Executive).

Bsb Bancorp Inc. – March 23, 2011 BSB Bancorp, MHC Belmont Center Two Leonard Street Belmont, MA 02478 BSB Bancorp Inc. Belmont Center Two Leonard Street Belmont, MA 02478 Belmont Savings Bank Belmont Center Two Leonard Street Belmont, MA 02478 (June 9th, 2011)

This letter confirms the engagement of Keefe, Bruyette & Woods, Inc. (KBW) to act as the financial advisor to BSB Bancorp, MHC (the MHC), BSB Bancorp Inc. (the Bancshares), and Belmont Savings Bank (the Bank) in connection with the proposed conversion and reorganization from the mutual holding company form of organization to a stock holding company form of organization pursuant to a Plan of Conversion and Reorganization to be adopted by the MHC, the Bancshares, and the Bank (the Reorganization). In order to effect the Reorganization, it is contemplated that the MHC will merge into the Bancshares and the Bancshares will merge into a new stock holding company (the Holding Company) and that the Holding Company will offer and sell shares of its common stock (the Common Stock) to eligible persons in a Subscription Offering, with any remaining shares offered to the general public in a Community Offering and if necessary, through a syndicate of broker-dealers organized by KBW (a Syndicated Co

Bsb Bancorp Inc. – BELMONT SAVINGS BANK Two Leonard Street Belmont, Massachusetts 02478-2511 DEFERRED COMPENSATION AGREEMENT (June 9th, 2011)

AGREEMENT made and entered into as of this 30th day of November, 1998, by and between Belmont Savings Bank, a Massachusetts savings bank corporation organized under Massachusetts General Laws, Chapter 168, with its principal office and place of business at Two Leonard Street, Belmont, Massachusetts (hereinafter referred to as the Bank) and Robert J. Morrissey, an individual who is currently serving as a Trustee of the Bank (hereinafter referred to as the (Trustee).

Bsb Bancorp Inc. – SEVERANCE AGREEMENT by and Between BELMONT SAVINGS BANK and HAL R. TOVIN (June 9th, 2011)

This Severance Agreement (the Agreement) is made and entered into as of , 2011 (the Execution Date), by and between Belmont Savings Bank, a Massachusetts-chartered savings bank with its principal administrative office at Two Leonard Street, Belmont, MA 02478 (together with its successors and assigns, the Bank) and Hal R. Tovin (Executive).

Bsb Bancorp Inc. – Belmont Savings Bank Deferred Compensation Plan for Members of the Board of Investment as Restated Effective February 15, 2008 (June 9th, 2011)

WHEREAS, Belmont Savings Bank (the Bank) established a Deferred Compensation Plan for members of the Board of Investment (the Plan) by instrument dated October 1, 1994, which Plan was amended by the First Amendment dated September 18, 1997 and the Second Amendment dated December 23, 1998; restated in its entirety on June 9, 2003; and restated in its entirety effective January 1, 2005; and

Bsb Bancorp Inc. – BELMONT SAVINGS BANK Two Leonard Street Belmont, Massachusetts 02478-2511 DEFERRED COMPENSATION AGREEMENT (June 9th, 2011)

AGREEMENT made and entered into as of this 1st day of December, 1998, by and between Belmont Savings Bank, a Massachusetts savings bank corporation organized under Massachusetts General Laws, Chapter 168, with its principal office and place of business at Two Leonard Street, Belmont, Massachusetts (hereinafter referred to as the Bank) and S. Warren Farrell, an individual who is currently serving as a Trustee of the Bank (hereinafter referred to as the (Trustee).

Bsb Bancorp Inc. – Restated Supplemental Retirement Agreement (June 9th, 2011)

THIS RESTATED SUPPLEMENTAL RETIREMENT AGREEMENT made and entered into as of the 23RD day of December, 2008, by and between Belmont Savings Bank, a Massachusetts savings bank with its principal place of business in Belmont, Massachusetts (hereinafter referred to as the Bank or in its capacity as the owner of the life insurance policies referred to herein, the Owner), and John A. Citrano, of Bedford, Massachusetts (hereinafter in his capacity as an executive employee of the Bank referred to as the Executive):

Bsb Bancorp Inc. – SEVERANCE AGREEMENT by and Between BELMONT SAVINGS BANK and ROBERT M. MAHONEY (June 9th, 2011)

This Severance Agreement (the Agreement) is made and entered into as of , 2011 (the Execution Date), by and between Belmont Savings Bank, a Massachusetts-chartered savings bank with its principal administrative office at Two Leonard Street, Belmont, MA 02478 (together with its successors and assigns, the Bank) and Robert M. Mahoney (Executive).

Bsb Bancorp Inc. – BELMONT SAVINGS BANK Two Leonard Street Belmont, Massachusetts 02478-2511 DEFERRED COMPENSATION AGREEMENT (June 9th, 2011)

AGREEMENT made and entered into as of this 19 day of December, 2006, by and between Belmont Savings Bank, a Massachusetts savings bank corporation organized under Massachusetts General Laws, Chapter 168, with its principal office and place of business at Two Leonard Street, Belmont, Massachusetts (hereinafter referred to as the Bank) and JOHN W. GAHAN III, an individual who is currently serving as a Trustee of the Bank (hereinafter referred to as the Trustee).

Bsb Bancorp Inc. – SEVERANCE AGREEMENT by and Between BELMONT SAVINGS BANK and CHRISTOPHER Y. DOWNS (June 9th, 2011)

This Severance Agreement (the Agreement) is made and entered into as of , 2011 (the Execution Date), by and between Belmont Savings Bank, a Massachusetts-chartered savings bank with its principal administrative office at Two Leonard Street, Belmont, MA 02478 (together with its successors and assigns, the Bank) and Christopher Y. Downs (Executive).

Bsb Bancorp Inc. – BELMONT SAVINGS BANK Two Leonard Street Belmont, Massachusetts 02478-2511 DEFERRED COMPENSATION AGREEMENT (June 9th, 2011)

AGREEMENT made and entered into as of this 1st day of December, 1998, by and between Belmont Savings Bank, a Massachusetts savings bank corporation organized under Massachusetts General Laws, Chapter 168, with its principal office and place of business at Two Leonard Street, Belmont, Massachusetts (hereinafter referred to as the Bank) and Patricia W. Hawkins, an individual who is currently serving as a Trustee of the Bank (hereinafter referred to as the (Trustee).

Bsb Bancorp Inc. – SEVERANCE AGREEMENT by and Between BELMONT SAVINGS BANK and CARROLL M. LOWENSTEIN, JR. (June 9th, 2011)

This Severance Agreement (the Agreement) is made and entered into as of , 2011 (the Execution Date), by and between Belmont Savings Bank, a Massachusetts-chartered savings bank with its principal administrative office at Two Leonard Street, Belmont, MA 02478 (together with its successors and assigns, the Bank) and Carroll M. Lowenstein, Jr. (Executive).

Bsb Bancorp Inc. – Belmont Savings Bank Supplemental Executive Retirement Plan (June 9th, 2011)

Bsb Bancorp Inc. – Incorporated Under the Laws of the State of Maryland Bsb Bancorp, Inc. Fully Paid and Non-Assessable Par Value $0.01 Per Share Cusip: The Shares Represented by This Certificate Are Subject to Restrictions, See Reverse Side (June 9th, 2011)

The shares evidenced by this certificate are transferable only on the books of BSB Bancorp, Inc. by the holder hereof, in person or by attorney, upon surrender of this certificate properly endorsed. The capital stock evidenced hereby is not an account of an insurable type and is not insured by the Federal Deposit Insurance Corporation or any other Federal or state governmental agency.

Bsb Bancorp Inc. – BELMONT SAVINGS BANK INCENTIVE COMPENSATION PLAN January 2011 (June 9th, 2011)

The purpose of the Belmont Savings Banks Incentive Compensation Plan (the Plan) is to provide incentives and awards to Officers and colleagues in order to support organizational and financial objectives as defined in the Business Plan. The plan is designed that participants do not take on undue risk to achieve payouts. All parties with responsibility for managing risk have incentives driven by risk metrics with clawbacks in the event losses arise in future periods.

Bsb Bancorp Inc. – Article 7. Stock Purchase Priorities (June 9th, 2011)

This Plan of Conversion (the Plan) provides for the conversion and reorganization of BSB Bancorp, MHC, a Massachusetts-chartered mutual holding company (the MHC), into the capital stock form of organization (the Conversion). The MHC currently owns 100% of the common stock of BSB Bancorp, Inc., a Massachusetts corporation (the Mid-Tier Holding Company), which owns 100% of the common stock of Belmont Savings Bank (the Bank), a Massachusetts-chartered savings bank, which is headquartered in Belmont, Massachusetts. Capitalized terms used but not defined in this Article 1 shall have the respective meanings set forth in Article 2 hereof.