The exchange ends the moment the taxpayer has actual or constructive receipt (i.e. direct or indirect use or control) of the proceeds from the sale of the relinquished property. The use of a QI is a safe harbor established by the Treasury Regulations. If the taxpayer meets the requirements of this safe harbor, the IRS will not consider the taxpayer to be in receipt of the funds. The sale proceeds go directly to the QI, who holds them until they are needed to acquire the replacement property. The QI then delivers the funds directly to the closing agent.