You might hear an agent say in a private treaty situation that the vendor will only exchange if the purchaser provides a “66W certificate”. The request is a reference to Section 66W of the Conveyancing Act 1919. The agent is telling you that the vendor doesn’t want to exchange contracts with a purchaser who retains the right to rescind (that is, cancel or get out of the contract). The vendor wants only a genuine purchaser who is committed to the purchase. It is not uncommon for contracts to exchange with the provision of 66W certificate. When acting for vendors solicitors often advise that the contract is only exchanged with a 66W.
66W is in Part 4, Division 8 of the Act which deals with the sale of “residential property“. Section 66S of that Division says that a Cooling Off period applies to the contract for sale of residential property in most situations (e.g. it doesn’t apply to a sale by auction or to large blocks of land).
In simple terms the cooling off period allows a purchaser to rescind the contract before 5pm on the fifth business day.
The cooling off period acts as a protection for the purchaser.
Section 66T of the Act says that a cooling off period doesn’t apply where a purchaser provides a certificate that complies with Section 66W of the Act. That certificate can only be provided by a solicitor (or barrister).