A retainer agreement is a long-term work-for-hire contract between a company and a client that retains ongoing services from you (as a consulting business) and provides you with a stable amount of payments.
Agreement periods usually run up to five years, but initial retainer agreements are often reviewed and renewed annually—usually at the end of the financial year. Retainer hours are usually spent on recurring tasks that aren't major projects but are important to the client.
Clients and professionals negotiate these terms to align expectations and ensure mutual satisfaction. The retainer may be refundable or non-refundable, contingent on the agreement specifics. The benefits of using retainer fees in professional relationships include security and predictability.