Retainer fee arrangements are one type of pricing model in wealth management, professional services, or family office services. They are a flat fee charged either initially or on a regular basis for agreed-upon services. Retainer fees differ, for example, from AUM fees in being unrelated to the level of assets a firm may manage or oversee for a client. They are typically more service-based or project-based than asset-based.

Retainer fees are usually agreed upon with the client before a project begins or in advance of a defined period of time, estimating what services may be provided. When the actual amount of services are significantly more or less than the estimated services, the retainer may be adjusted for the following service period or the client may be charged an extra fee.  Prudent ongoing management of the balance between fees and services is useful for both the provider and the client.