Why does brand deal commission run 10 to 20 percent and not 5 percent or 35 percent? Three structural reasons set the range.

The lower bound (10 percent). Below 10 percent, the agency cannot cover the cost of negotiating the deal. A typical brand deal negotiation involves the agency's salesperson, contract reviewer, often outside legal counsel, and post-deal account management. Below 10 percent commission, those costs eat the margin and the agency loses money on the deal. Any agency offering below 10 percent is either operating at a loss to acquire the creator or is providing a stripped-down service.

The upper bound (20 percent). Above 20 percent, the math the streamer ran in lesson 3.2 starts breaking down. The streamer needs the agency to generate enough incremental revenue to cover the commission and still come out ahead. Commissions above 20 percent only work for very specific high-leverage cases (top-tier creators or deeply negotiated specialty deals).

The 15 percent middle. Most full-service blended rates settle at 15 percent because that rate is sustainable for the agency and net-positive for the streamer at most income levels.

If you see a proposal at 25 to 30 percent commission, ask what specifically the agency is doing that justifies the premium. Sometimes the answer is good (specialty negotiation, exclusive market access). Sometimes it is not. Either way, the question gets asked.