Can my landlord charge me a fee just for approving the assignment to my buyer?

Often yes, if your lease says so. Many commercial leases entitle the landlord to recover its reasonable legal and administrative costs of reviewing and documenting a proposed assignment, and that fee is generally treated as a legitimate condition of consent rather than an obstruction of it. The key word is "reasonable" — a fee tied to actual costs incurred is very different from a fee pitched as a way to extract extra value from the sale.

Whether a fee crosses the line into an improper condition depends on your lease's exact wording and, where the lease incorporates a "not unreasonably withheld" standard for consent, on whether an inflated fee could itself be seen as part of an unreasonable refusal. This is fact-specific and not something a general rule can settle for you.

Before agreeing to pay, ask for a breakdown of what the fee actually covers, and check your lease for any cap or reasonableness qualifier on assignment-related costs. A Treadstone business lawyer can review the request and push back if the number looks disconnected from the landlord's actual costs.