In March 2025, the governing documents of the Management Holdcos were each amended to allow for the issuance of new Profits Interest Units (“PIUs”) to its members, which are comprised of the Managing Directors of the Company. During the year ended December 31, 2025, PIUs were issued to certain Managing Directors of the Company. The PIU grants in the Management Holdcos were deemed to be transactions incurred on behalf of the Company and the grant of the PIUs to the Company’s Managing Directors are accounted for as equity-based compensation in accordance with ASC 718. As a result, the expense related to the PIU grants by the Management Holdcos, as Andersen Tax Holdings LLC's controlling unitholders, were reflected in the Company’s consolidated financial statements and recognized as a non-cash contribution by the Management Holdcos.

The PIUs were created to provide additional allocations of distributable profits and losses of Andersen Tax Holdings LLC to the Managing Directors in proportion to their total units, which include the PIUs. The economic terms of the PIUs give the holders an equity ownership in the Company, an economic interest in the future profits and losses of the Company and holders receive value from their awards by receiving distributions. The PIUs vest immediately and are subject to forfeiture upon termination of employment, either voluntary or involuntary.

The expense related to the PIUs was measured based on their estimated grant date fair values and was recognized in full on the grant date as there was no required service or vesting to participate in the benefits. Equity-based compensation expense is recognized within cost of services and sales, general and administrative expenses on the consolidated statements of operations based on the function of those receiving awards. The Company used a Probability-Weighted Expected Return Method (“PWERM”) model to determine the grant date fair value of the PIUs.

PWERM is a scenario-based methodology that estimates the fair value of PIUs based upon an analysis of future values for the Company, assuming various outcomes. The value for the PIUs was based on the probability-weighted present value of expected future investment returns considering each of the possible outcomes available as well as the

rights of each class of units. The future value of the units under each outcome was discounted back to the valuation date at an appropriate risk-adjusted discount rate and probability weighted to arrive at an indication of value for the PIUs. A discount for lack of marketability of the PIUs was then applied to arrive at an indication of value for the PIUs.

The weighted-average grant date fair value of the PIUs issued during the year ended December 31, 2025 was $766.54 per unit. The Company issued 178,025 PIUs during the year ended December 31, 2025. The Company recognized $104.5 million of equity-based compensation expense in cost of services and $32.0 million in sales, general and administrative expense during the year ended December 31, 2025.

On December 6, 2025, the board of directors of Andersen Group Inc. approved the Company’s 2025 Equity Incentive Plan. The 2025 Equity Incentive Plan provides for the grant of nonstatutory stock options (NSOs), stock appreciation rights (SARs), restricted shares, restricted stock units (RSUs) and other equity-based awards. The Company has reserved 6,700,000 shares of Class A common stock in connection with the approval of the 2025 Equity Incentive Plan. On the first day of each January during the term of the 2025 Equity Incentive Plan, beginning on January 1, 2026 and ending on (and including) January 1, 2035, the number of shares of Class A common stock that may be issued under the 2025 Equity Incentive Plan will increase by a number of shares equal to the lesser of (a) 5% of the outstanding shares of all classes of common stock on the last day of the immediately preceding fiscal year or (b) such lesser number of shares (including zero) that the plan administrator determines for purposes of the annual increase for that fiscal year. The Company will recognize forfeitures as they occur.

Concurrently with the IPO, the Company granted new RSUs to employees. The RSUs granted in 2025 have a time-based vesting requirement wherein 1/6th of the total number of RSUs subject to the award will vest on each annual anniversary of the vesting commencement date, subject to the recipient’s continuous service as an employee to the Company, a parent, subsidiary or affiliate through the applicable vesting date. Upon vesting, the RSUs are convertible into Class A common stock; unvested RSUs are not considered outstanding shares of Class A common stock.

The fair value of the RSUs was based on the fair value of a share of Class A common stock at the time of grant, which equates to a weighted-average grant date fair value of $16.00 per unit. Total compensation expense for RSUs was approximately $0.6 million for the year ended December 31, 2025, of which $0.5 million is included in cost of services and $0.1 million is included in sales, general and administrative expense in the consolidated statement of operations. The unamortized compensation cost related to RSUs of $86.1 million as of December 31, 2025 is expected to be recognized over a weighted-average period of approximately 5.9 years.

Concurrently with the IPO, AT Umbrella LLC issued AT Umbrella LLC LTIP Units to Aggregator in connection with an earlier appointment of additional Managing Directors during 2025, and Aggregator issued corresponding Aggregator LTIP Units to such Managing Directors representing such claim to AT Umbrella LLC LTIP Units. 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.

AT Umbrella LLC LTIP Units 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. LTIP Units designated as "Catch-Up Units" are subject to a provision allowing their holder to receive additional distributions after satisfying the hurdle amount of the unit. Once the hurdle amount is surpassed, a catch-up adjustment ensures that the holder of the Catch-Up Unit receives distributions equivalent to what they would have received if the hurdle amount had not been applied, up to the agreed-upon cumulative amount.

The fair value of the LTIP Units was based on the fair value of a share of Class A common stock of Andersen Group Inc. at the time of grant, which equates to a weighted-average grant date fair value of $16.00 per unit. The LTIP Units granted in 2025 are subject to a hurdle amount of $16.00 per unit, which was specified at issuance and represents the threshold over which an LTIP Unit is allocated income or is entitled to distributions.

Total equity-based compensation expense for LTIP Units was approximately $0.1 million for the year ended December 31, 2025, which is included in cost of services in the consolidated statement of operations. The unamortized compensation cost related to LTIP Units of $14.0 million as of December 31, 2025 is expected to be recognized over a weighted-average period of approximately five years.

In connection with the Reorganization Transactions described in Note 1, Andersen Tax LLC incurred compensation expenses as a result of the exchange of common units and PIUs of the Management Holdcos for new Class X Aggregator Units with Managing Directors of Andersen Tax LLC, of which a portion of the new interests are subject to vesting conditions. These Class X Aggregator Units generally vest 1/5th on each annual anniversary of their vesting commencement dates.

The portion of units subjected to service-based vesting conditions results in incremental compensation expense to be recognized over the requisite service period. The Company incurred $10.2 million of compensation expense for Class X Aggregator Units for the year ended December 31, 2025, of which $9.7 million was recognized in cost of services and $0.5 million was recognized in sales, general and administrative expenses on the consolidated statement of operations. The unamortized compensation cost related to Class X Aggregator Units of $708.9 million as of December 31, 2025 is expected to be recognized over a weighted-average period of approximately 4.7 years. The grant date weighted average fair value

In connection with the Reorganization Transactions described in Note 1, Andersen Tax LLC incurred certain equity restructuring expenses totaling approximately $193.2 million as a result of the exchange of historical equity interests of the Management Holdcos for new Class H Aggregator Units (for which AT Umbrella issued to Aggregator the Holdover Note) and the Class X Aggregator Units (for which, together with the Member Notes, AT Umbrella issued to Aggregator the Capital Account Notes). The new Class H Aggregator Units include a higher income allocation to unit holders than under the previous Management Holdco units held by such unit holders, which results in an incremental one-time expense. The Company recorded $162.3 million during the year ended December 31, 2025 for these Class H Aggregator Units, which is recorded as equity restructuring costs on the consolidated statement of operations. The value for the equity restructuring expense associated with Class H Aggregator Units was estimated using a discounted cash flow methodology.

Certain holders of historical equity interests at the Management Holdcos also received Class X Aggregator Units and a return of contributed capital which resulted in an incremental one-time expense for these Class X Aggregator Units of $30.9 million, which is recorded as equity restructuring costs on the consolidated statement of operations. The value for the equity restructuring expense associated with Class X Aggregator Units was estimated as the difference between the value of the Class X Aggregator Units and the value of the historical equity interests at the Management Holdcos.