The sum due to the retiring partner includes:

(A) His share of profits up to the date of retirement.

(B) His share of goodwill;

(C) His share of accumulated profits;

(D) His share in the gain of revaluation of assets and liabilities;

Choose the correct answer from the options given below:

The correct answer is (A), (B), (C) and (D).

When a partner retires from a partnership firm, they are entitled to receive their share of the firm's assets, accumulated profits, and other earnings up to the date of their retirement. The total amount due to the retiring partner is calculated by adjusting their capital account with several key items:

1. His share of profits up to the date of retirement (A): The retiring partner has contributed to the business operations during the current financial year until the day they leave. Therefore, the profit earned by the firm during this interim period is calculated, and the retiring partner's share is credited to their account.

2. His share of goodwill (B): Goodwill is the reputation and extra earning capacity built by the firm over the years through the joint efforts of all partners. Upon retirement, the retiring partner compensates the remaining partners for relinquishing their future share of profits by receiving their share of goodwill.

3. His share of accumulated profits (C): Any undistributed profits, reserves, or general reserves accumulated over past years belong to all partners in their profit-sharing ratio. The retiring partner is entitled to their share of these accumulated profits and reserves.

4. His share in the gain of revaluation of assets and liabilities (D): When a partner retires, the firm's assets and liabilities are revalued to reflect their current market values. Any net gain (or loss) arising from this revaluation process is distributed among all partners, including the retiring partner, in their old profit-sharing ratio.

Since all the listed components—(A), (B), (C), and (D)—are credited to the retiring partner's capital account to determine the total sum due to them, the correct choice is (A), (B), (C) and (D).