Change in firm constitution: assessment is made on the firm as constituted at the time of assessment, death exception applies. Assessment must be made on the firm as constituted at the time of assessment where a change in constitution has occurred. A change occurs if partners cease or are admitted while some original partners continue, or if partners continue but their shares change. Dissolution on the death of a partner is excluded from this definition and is governed by separate succession provisions; reconstitution after dissolution is treated as a change in constitution for assessment purposes.