Payment in kind only frees the debtor by the liquid amount of the transferred assets.Despite this, it is unquestionable that the dation in payment is perfectly permissible in our legal system and often quite frequent in practical reality. That being so, it is easy to assume that the jurisprudence of the Supreme Court has been abundant in this area and the doctrine has leveraged it to infer the requirements which compliments must be understood so in an obligacional relationship the dation resource can be used in payment. Basically these requirements are as follows: 1. agreement between the creditor and the debtor to be extinguished the original obligation, without giving origin to a new obligacional relationship, by means of the agreement replace the initial provision by another. Therefore, the dation in payment excludes the novation. 2 Transmission or simultaneous delivery of the object of the new benefit, because if the debtor only commits itself to it would be against a course of Novation and as such non-payment in kind. 23 September 2002 STS offers the following concept of the dation in payment in these terms: this legal figure, according to the construction of the civil jurisprudence, operates when the business will of the parties agree to carry out the satisfaction of a pending debit, and the creditor accepts to receive certain assets of its property of the debtorwhose full domain is transmitted to apply it to the total extinction of the credit, acting this credit with equal function than the price in the sale (in identical sense, the 19-10-1992 STS 26-6-1993, 2-12-1994, 8-2-1996, among others).In practical reality the new provision usually consist of deliver or give something. However, it is perfectly acceptable that the new provision is of another nature as an obligation to do, for example. In this sense the STS of October 1, 2009 States that: in order to the principle of the autonomy of the will, the parties can be configured a dation in payment of services which the detail and amount are not perfectly determined although the parties know, accept and agree to extinguish the obligation of payment of the price, still not well determined.