Final answer:
The term for unwritten authority to perform necessary tasks within an agency agreement is implied authority, which is essential for the fluid operation of business affairs.
Step-by-step explanation:
The unwritten authority a producer or an agent has to perform tasks that are reasonably necessary to carry out the express instructions of an agency agreement is known as implied authority. This type of authority isn't explicitly stated but is assumed to be granted in order to fulfill the duties outlined in the agreement. Implied authority allows for the smooth operation of a business by empowering agents to perform incidental acts that facilitate the completion of their tasks without the need for specific consent from the principal for every action.
For example, if a sales agent has an agreement to sell a product, the agent's implied authority could include the ability to negotiate prices with potential buyers, arrange for delivery of goods, and provide necessary customer service, as these are all necessary to complete the sale effectively.