For what type of policy, in what state, commerial or personal lines, monoline or package, what carriers, how large is the MGA?
Someone once said to me: Garbage In, Garbage Out. You have to ask thorough questions on this forum to get a useful and helpful response. The State and Type of Insurance you are asking about is often helpful as well.
I believe the average MGA makes 20%, and splits with the retail agent, giving them 10%. Could be higher, maybe 25% on some products, or lower.
MGA for personal lines? Do they have a standard/preferred market? Most MGA' s for personal lines involve a lot of extra work on each renewal and only offer non admitted.