The broker commission is the success-based fee earned by a real estate agent, payable only upon conclusion of a contract. In Germany, legislation since 2020 requires buyer and seller to split the commission equally for residential purchases, typically ranging from three to seven percent of the sale price depending on the region. For rental agreements, the 'ordering party principle' applies, meaning whoever hired the agent bears the cost. The commission must be agreed upon in a brokerage contract and becomes due upon notarization. For buyers, it qualifies as an ancillary acquisition cost and may be considered for tax purposes as part of the property's total cost basis.