BL BlackLine Inc

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 the disclosures provided in a prior cover page.

 Names of Reporting Persons.

 Therese Tucker

 Check the Appropriate Box if a Member of a Group (See Instructions)

 (a) ☐  (b) ☒

 SEC Use Only

 Citizenship or Place of Organization

 Ms. Tucker is a U.S. Citizen

Number of

Shares

 Beneficially 

Owned by

Each

Reporting

Person

With:

 Sole Voting Power

 3,447,979¹

 Shared Voting Power

 1,409,193²

 Sole Dispositive Power

 3,447,979¹

 Shared Dispositive Power

 1,409,193²

 Aggregate Amount Beneficially Owned by Each Reporting Person

 4,857,172^1,2

 Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)

 ☐

 Percent of Class Represented by Amount in Row (9)

 8.0%³

 Type of Reporting Person (See Instructions)

 IN

Consists of (i) 134,443 shares of Common Stock held by the Reporting Person; (ii) 80,531 shares of Common Stock issuable pursuant to restricted stock units that are subject to vesting conditions that may be satisfied within 60 days of December 31, 2023; (iii) 468,546 shares of Common Stock subject to options which are exercisable within 60 days of December 31, 2023; (iv) 577,200 shares of Common Stock held by the Isaac Tucker 2012 Irrevocable Gift Trust; (v) 577,200 shares of Common Stock held by the Roseanna Tucker 2012 Irrevocable Gift Trust; (vi) 1,509,881 shares of Common Stock held by the Brian and Therese Tucker Living Trust; and (vii) 100,178 shares of Common Stock held by the Brian and Therese Tucker Charitable Remainder Trust.

Consists of (i) 874,128 shares of Common Stock held by the Tucker Legacy Trust, dated 12/30/2014; (ii) 54,074 shares of Common Stock held by the Claire Seimetz 2015 Trust; (iii) 250,916 shares of Common Stock held by the Tucker-Seimetz Safety Net Trust; (iv) 100,178 shares of Common Stock held by the Tucker Family CLAT; and (v) 129,897 shares of Common Stock held by the Tucker Legacy Trust II.

The percentage is calculated using 60,515,105 shares of Common Stock issued and outstanding as of December 31, 2023.

If this statement is filed pursuant to §§240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:

Ownership

Amount beneficially owned: 4,857,172^1,2

Percent of class: 8.0%³

Number of shares as to which the person has:

Sole power to vote or to direct the vote 3,447,979¹

Shared power to vote or to direct the vote 1,409,193²

Sole power to dispose or to direct the disposition of 3,447,979¹

Shared power to dispose or to direct the disposition of 1,409,193²

Consists of (i) 134,443 shares of Common Stock held by the Reporting Person; (ii) 80,351 shares of Common Stock issuable pursuant to restricted stock units that are subject to vesting conditions within 60 days of December 31, 2023; (iii) 468,546 shares of Common Stock subject to options which are exercisable within 60 days of December 31, 2023; (iv) 577,200 shares of Common Stock held by the Isaac Tucker 2012 Irrevocable Gift Trust; (v) 577,200 shares of Common Stock held by the Roseanna Tucker 2012 Irrevocable Gift Trust; (vi) 1,509,881 shares of Common Stock held by the Brian and Therese Tucker Living Trust; and (vii) 100,178 shares of Common Stock held by the Brian and Therese Tucker Charitable Remainder Trust.

Consists of (i) 874,128 shares of Common Stock held by the Tucker Legacy Trust, dated 12/30/2014; (ii) 54,074 shares of Common Stock held by the Claire Seimetz 2015 Trust; (iii) 250,916 shares of Common Stock held by the Tucker-Seimetz Safety Net Trust; (iv) 100,178 shares of Common Stock held by the Tucker Family CLAT; and (v) 129,897 shares of Common Stock held by the Tucker Legacy Trust II.

The percentage is calculated using 60,515,105 shares of Common Stock issued and outstanding as of December 31, 2023.

Ownership of Five Percent or Less of a Class

Ownership of More than Five Percent on Behalf of Another Person

Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on By the Parent Holding Company or Control Person

Identification and Classification of Members of the Group

Notice of Dissolution of Group

Certifications