simply put, a retainer agreement is a way to be paid in advance for work you’ll do in the future. another benefit of using a retainer agreement is it allows you to plan your work in advance. since the relationship is already there, entering into a retainer agreement with them solidifies their loyalty to you. if a client with a retainer agreement decides to end the contract and leave you, there goes a good chunk of your income. the best type of work for a retainer agreement is anything that is done on a regular basis. you may be inclined to offer a discount to your client should you go over the time/amount specified.