[solost]

A retainer generally implies a fixed fee for up to "x" amount of service time. The company risks part of their investment if they don't use all the time available on the monthly retainer. However that risk is offset by having the service provider generally available as needed.

My recommendation to you is to mentally set your hourly rate and then multiply it by the total number of hours you are willing to give them, regardless of the number of hours they want. So if you are willing to give them 5 days (40 hours) of service a month, then set your rate at that point (This should always be a fixed number, not hourly billing, so you and they know the exact cost every month and you can be prepaid).

Remember when setting your rate, odds are they will use every single hour available and if you are not getting other services, then your rate should be higher than your salaried rate was because the company is no longer having to eat all of the other “hidden expenses” and you will be taking on new taxes such as an additional 7.5% for being self employed. Consider lowering your rate for continued access to services like health insurance or retirement plans.

Decline any financial compensation related to performance, only go for a fixed fee, else you may find yourself distracted or side tracked and working extra hours that you never intended to, to achieve some financial goal or project closure. The hardest part about working retainers is actually limiting yourself to the contract requirements and no more, especially when working with people that you have real personal relationships with.