A Massachusetts residential purchase agreement is a legal document that secures a real estate transaction between a buyer and a seller. The purchase and sale agreement deals with the title to the property and the deed.It documents the transaction's stipulations, including the sales price, movein date, and items that will be included with the property. There are two main offer forms used in Massachusetts. The completed form will relay the unique terms and conditions of the sale, including the purchase price and the manner of payment.