Acquisition of real estate today introduces the usual mandatory obligations between the seller and the buyer, and is regulated by Obligations law. Obligations arise on the basis of legal affairs. The most important legal basis of the mandatory relationship is the contract, the corresponding statement of the will of the parties or the contractual obligation. The seller sells the thing to the buyer by purchasing the property, and the buyer undertakes to pay the price. By concluding a sales contract, the seller assumes the obligation to hand over things, and the buyer has the obligation to pay the money or the seller is entitled to ask for the price, and the buyer is entitled to request the surrender of the thing, which means that each contracting party is also the creditor and the borrower. Merchandise is a two-way compulsory and a toll contract because the seller assumes the obligation to hand over things, and the buyer is obligated to pay the price. The subject of a contract may be a thing in circulation, and the sale may also relate to the future thing and the right whereby the seller commits the buyer to obtain the sold right. The very nature of the purchase contract must be determined or determinable. The thing is determined if its quantity is determined. The purchase contract must also specify the price the customer has to pay, or at least determinable. A certain price is established at a fixed amount. The price is determinable if the contract contains enough information to determine the price. Croatian law provides that a non-binding relationship ceases when a debtor is required to perform his duties, as well as other law-specific cases. The obligation ceases by consent of the will of the participant in the compulsory relationship, fulfillment and in other legally defined cases, such as the decision, the dismissal, the dismissal of the debt. The guarantee, pledge and other subsidiary rights shall be terminated by termination of the principal obligation.