Organization and Business Description

12 Months Ended

Dec. 31, 2025

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Organization and Business Description

Organization and Business Description

Andersen Group Inc. was formed on April 16, 2025 for the purpose of facilitating an initial public offering (“IPO”) and other related transactions in order to operate the business of AT Umbrella LLC. Andersen Group Inc. is a holding company, and its sole material asset is its indirect ownership interests in Andersen Tax Holdings LLC through its ownership of approximately 11.4% of the Class X Umbrella Units in AT Umbrella LLC, which in turn owns all ownership interests in Andersen Tax LLC and its 100% wholly owned subsidiaries, (collectively, the “Company”). The Company is a national professional services firm focused on providing a wide range of tax, valuation, financial advisory, and related consulting services (including certain services acting as a registered investment adviser). As of December 31, 2025, the Company has 26 offices in 15 states and the District of Columbia.

Prior to the Company completing its IPO and Up-C restructuring (the “Reorganization” or “Reorganization Transactions”), the Company historically conducted business through Andersen Tax Holdings LLC and its subsidiaries, including Andersen Tax LLC. Andersen Tax Holdings LLC was formed on December 31, 2007, to execute the acquisition of an existing business by MD Management LLC and MD Investment LLC (collectively, the “Management Holdcos”). On June 26, 2013, Andersen Tax LLC became a member firm in Andersen Global, a Swiss verein established under articles 60-79 of the Swiss Civil Code. Each member firm provides services in a defined geographic area and is subject to the laws and professional regulations of the particular country or countries in which it operates. The Articles of Association of Andersen Global provide for the autonomy of its member firms and specifically require each member firm to retain and remain solely responsible for its own legal obligations to third parties and its partners or managing directors and employees, arising before or after the formation of Andersen Global, including all debts and obligations.

Initial Public Offering

On December 18, 2025, the Company completed its IPO of 12,650,000 shares of Class A common stock at an offering price of $16.00 per share, including 1,650,000 shares of Class A common stock issued pursuant to the underwriters' over-allotment option. The Company received net proceeds of $188.2 million, net of underwriting discounts and commissions of $14.2 million, but before deducting offering costs of $9.9 million. The Company used the proceeds to purchase 12,650,000 newly-issued membership units of AT Umbrella LLC (“Class X Umbrella Units”) at a price per unit equal to the IPO price, net of underwriting discounts and commissions.

Summary of the Reorganization and Other Transactions Completed in Connection with the IPO

In connection with the IPO, a series of transactions comprised of a reorganization, offering and other financing transactions were completed. The following summarizes the Reorganization Transactions that were completed as of the date of IPO:

•Andersen Group Inc. amended and restated its certificate of incorporation, pursuant to which it is authorized to issue two series of common stock, Class A and Class B. Class A common stock has one vote per share and is entitled to economic rights. Class B common stock has ten votes per share and is not entitled to economic rights.

•The Management Holdcos merged into Andersen Aggregator LLC (“Aggregator”). Existing common units and profits interest units were converted to Class X Aggregator Units. A percentage of the new Class X Aggregator Units were subject to vesting conditions for active managing directors who perform services for Andersen Tax LLC.

•AT Umbrella LLC was formed. Andersen Aggregator LLC contributed 100% of its equity interests in Andersen Tax Holdings LLC to AT Umbrella LLC in exchange for Class X Umbrella Units. Immediately after this contribution, AT Umbrella LLC became the managing member of Andersen Tax Holdings LLC.

•Andersen Group Inc. issued to Andersen Aggregator LLC 98,302,500 shares of Class B common stock in exchange for the payment by Aggregator of the aggregate par value of the Class B common stock that is received.

•The Management Holdcos issued to each of their members a promissory note in a principal amount equal to such member’s and its related transferee's aggregated capital account balance in respect of such Management Holdco as of December 16, 2025, with repayment over a seven-year period for each family of related notes with a principal

balance of at least $550,000, either a three- or seven-year period for each family of related notes with a principal balance of less than $550,000 and a period of between two to seven years for notes issued to certain retiring and retired managing director members of the Management Holdcos (the “Member Notes”). Additionally, AT Umbrella LLC issued corresponding notes to Aggregator (the “Capital Account Notes”) with aggregate principal amounts of approximately $187.8 million, equal to the sum of the aggregate principal amounts of the Member Notes, to be paid over the same two- to seven-year period, respectively. The Capital Account Notes accrue interest between 6.31% to 7.50%.

•In connection with the reorganization of the Management Holdcos, Aggregator issued Class H Aggregator Units entitling certain retiring and retired managing director members of the Management Holdcos subject to certain terms and conditions, to certain cash distributions paid over a period of up to seven years relating to payment of certain post-service obligations.

•AT Umbrella LLC issued to Aggregator a promissory note in a principal amount of approximately $162.3 million with repayment occurring over an eight-year period relating to payment of the above-mentioned post-service obligations to certain retiring and retired managing director members of the Management Holdcos (the “Holdover Note”). The Holdover Note accrues interest at 7.63%.

•Andersen Group Inc. entered into a Tax Receivable Agreement (“TRA”) with Aggregator concurrent with the Reorganization Transactions, which requires the Company to pay to certain holders of Class X Umbrella Units who are or may become parties to the TRA (the “TRA Parties”) from time to time 85% of the amount of tax benefits, if any, that are actually realized (or in some circumstances that are deemed to realize) as a result of (i) any increase in tax basis in the assets of AT Umbrella LLC and its flow-through subsidiaries resulting from purchases of Class X Umbrella Units from such Class X Umbrella Unit holders with the proceeds of the IPO or exchanges of Class X Umbrella Units for shares of Class A common stock or cash in the future; and (ii) certain other tax benefits related to entering into the TRA, including tax benefits attributable to payments that the Company will make under the TRA.

Class X Umbrella Units held by pre-IPO common unitholders and profits interest units at AT Umbrella LLC (“LTIP Units”) are exchangeable for Class A common stock from Andersen Group Inc.

The Reorganization Transactions were accounted for as a transaction between entities under common control. As a result, the financial statements for periods prior to the IPO and the Reorganization have been adjusted to combine the previously separate entities for presentation purposes. As the managing member, Andersen Group Inc. operates and controls all of the business and affairs, and through AT Umbrella LLC and its subsidiaries, conducts the business of Andersen Tax LLC. Andersen Group Inc. consolidates AT Umbrella LLC and its subsidiaries in its consolidated financial statements and reports a redeemable noncontrolling interest related to the Class X Umbrella Units held by the pre-IPO common unitholders and the LTIP Units in the consolidated financial statements.

The following summarizes the other transactions completed in connection with the IPO:

•AT Umbrella LLC granted LTIP Units to Aggregator in connection with the earlier appointment of additional managing directors during 2025, and Aggregator issued corresponding Aggregator LTIP Units to such managing directors. Andersen Group Inc. issued to Aggregator shares of Class B common stock equal in number to the maximum number of Class X Umbrella Units issuable upon exchange of such LTIP Units issued to Aggregator in exchange for the payment by Aggregator of the aggregate par value of the Class B common stock that is received. LTIP Units in AT Umbrella are economically similar to stock options. Each LTIP Unit has a per unit hurdle price, which is economically similar to the exercise price of a stock option.

•Andersen Group Inc. granted 5,440,720 restricted stock units (RSUs) under the 2025 Equity Incentive Plan concurrent with the IPO.