Brokerage commissions are treated differently. Historically brokers have charged a Brokerage Fees Tax Deductible for trading that was either added to the cost of purchasing stock or deducted from the proceeds of a sale. These brokerage fees were deducted when the acquired stock was sold, forming part of the cost of the shares and reducing the proceeds. It’s generous because you may not have sold anything in your portfolio, although it may have gained in value. Yet you still can secure a current deduction that previously was deferred until the taxable sale.