Can my buyer negotiate a lower transfer fee if they're already an existing franchisee of the same brand?

Possibly, though whether this happens depends entirely on the franchisor's own practices and what your specific franchise agreement's fee provision actually allows for negotiation. Franchisors sometimes do offer more favourable transfer terms to a buyer who is already an existing, proven franchisee within the same system, since the franchisor already has a working relationship and track record with that buyer, which can reduce the perceived risk and administrative work of onboarding a completely new operator.

This isn't a right your buyer can necessarily insist on, though, unless your agreement's fee structure specifically distinguishes between new and existing franchisees, or the franchisor has an established, consistent practice of doing so across the system. Where the fee is fixed regardless of the buyer's status, an existing franchisee generally pays the same as anyone else, however established their relationship with the franchisor already is.

Because this depends heavily on the specific franchisor's practices and your agreement's wording, it's worth asking directly rather than assuming a discount applies. A Treadstone business lawyer can help clarify what your agreement actually permits and support the negotiation.