The purpose of a subject clause contained in an offer to purchase is to set out a specific condition that must be fulfilled before the sale can go through.
One common subject clause you might encounter is one in which the purchaser make the sale conditional upon their finding the exact amount and type of financing which will enable them to purchase your home.
Remember that, if you accept an offer which contains a subject clause, you are effectively taking your property off the market for the period in which the purchasers are attempting to meet the condition they have set. Therefore, you should ensure that an agreed upon time for the condition to be met is specified in the offer to purchase.
If one of the conditions contained in a subject clause cannot be met after every reasonable effort has been made to do so, the contract ends and there is no legal obligation to complete the purchase of sale.
As a seller, you may wish to accept an offer containing a subject clause (e.g. subject to the purchasers selling their house) yet still leave yourself free to consider other offers, just in case the purchasers are unable to remove the condition. You can do this by having the buyer agree to inserting a time clause in the contract. A time clause will permit you to require the buyer to remove all subject conditions within a short, specified time period if you receive another offer that you would like to accept. If the buyer does not remove the conditions within that time, the conditional contract comes to an end and you are free to accept the second offer.