Charge of tax where members' shares are indeterminate: association income taxed at maximum marginal rate or higher. A new provision taxes the total income of an association of persons or body of individuals at the maximum marginal rate where members' individual shares in whole or part of the income are indeterminate or unknown, but applies any higher tax rate that is applicable to a member's own total income. Where shares are determinate, the provision taxes the association at the maximum marginal rate if a member's income (excluding his share) exceeds the non-taxable threshold, and apportions higher rates to portions attributable to members chargeable at rates above the maximum marginal rate.