This act was passed to assert the authority of the British government to tax its subjects in North America after it repealed the much-hated Stamp Act. The purpose of the Declaratory Act of 1766 was to affirm that Great Britain had complete authority to tax its American colonies.All related (37). Recommended. On March 18, 1766, Parliament repealed the Stamp Act and passed the Declaratory Act. The purpose of the tax was to pay for British military troops stationed in the American colonies after the French and Indian War. Declaratory Act (1766). The Declaratory Act. The Declaratory Act of 1766 served a significant role in defining the relationship between the British Parliament and the American colonies. The American Colonies Act 1766 (6 Geo. 3. c. The document prompts a perspective from a New York colonist in 1766 regarding the Stamp, Quartering, and Declaratory Acts.