Only contracts entered into by the Contracting Authorities, as defined above, can be SARA contracts. It does not matter whether or not they are Public Administrations, or private or administrative contracts. The important thing is that they are Adjudicating Powers.

Only the following contracts regulated in the Public Sector Contracts Law (LCSP) can be SARA contracts:

To be SARA contracts: (amounts updated January 1, 2020).

After the entry into force in 2007 of the Public Sector Contracts Law (LCSP), the traditional definition is relegated simply to public contracts concluded by Public Administrations. Along with them, there are other public contracts that, despite being concluded by Entities whose ownership is public, have a private legal regime. Thus, more appropriately, we must speak of "public sector contracts" that can be concluded by various types of subjects:

The Adjudicating Powers are:

Only contracting authorities may carry out Contracts Subject to Harmonized Regulation") (SARA Contracts), which are those to which the Community Directive regulating public contracts applies.

The rest of the entities whose ownership is public will not be able to carry out SARA contracts.

Article 70.2 of the consolidated text of the Public Sector Contracts Law")[2]​ establishes that in order to maintain the classification, the maintenance of the economic and financial solvency") and, every three years, that of the technical and professional solvency") of the company must be justified.[3]​.

The legal regime of public contracts. In order to address it, we must distinguish between administrative contracts and private contracts.

They are those signed by a Public Administration, with some specialty, since there are contracts signed by a Public Administration that must be considered private (such as those for artistic creation and interpretation, shows or certain financial services).

They are completely governed by the Public Sector Contracts Law (or, if it is a special administrative contract not classified therein, by its specific regulations), its implementing provisions and by the rest of the administrative law regulations. Only in cases of interpretative gaps should private law be resorted to.

In this sense, we choose to define the contractual concept of the Public Administration as the agreement of two or more parties to create, regulate, modify or extinguish a patrimonial legal relationship, of which at least one of the parties is an entity of the Public Administration.

It should be noted that, according to this definition, it is clear that the distinctive element of the contract is not the fact that the administrative entity that celebrates the contract has special prerogatives in its favor, since it may or may not even condition such prerogative to certain circumstances, but that at least one of the parties that celebrate the contract is a Public Administration.

They are private contracts:

This type of private contracts is where the theory of separable acts has been designed, essential to understand their legal regime. Under the same:

This is important since administrative law grants the Administration a series of prerogatives during contractual execution (unilateral interpretation, unilateral modification, imposition of penalties...) that cease to exist in the private contract. Therefore, the public sector contract cannot be defined as a contract where one of the parties has exorbitant powers, since that can only be predicated of the administrative contract which, as we see, is a subtype of public contract.

The importance that the European Union gives to the contractual activity of the States is such that there is a specific rule, which we will call the Community Contract Directive (Directive 2004/18/EC), dedicated to regulating this matter. This is due to the community's commitment to achieving freedom of access to public tenders and true market competition. Public contracts subject to this rule are called SARA contracts. However, not all contracts entered into by the public sector are subject to it. There are subjective, amount and objective requirements.

Only contracts entered into by the Contracting Authorities, as defined above, can be SARA contracts. It does not matter whether or not they are Public Administrations, or private or administrative contracts. The important thing is that they are Adjudicating Powers.

Only the following contracts regulated in the Public Sector Contracts Law (LCSP) can be SARA contracts:

To be SARA contracts: (amounts updated January 1, 2020).

After the entry into force in 2007 of the Public Sector Contracts Law (LCSP), the traditional definition is relegated simply to public contracts concluded by Public Administrations. Along with them, there are other public contracts that, despite being concluded by Entities whose ownership is public, have a private legal regime. Thus, more appropriately, we must speak of "public sector contracts" that can be concluded by various types of subjects:

The Adjudicating Powers are:

Only contracting authorities may carry out Contracts Subject to Harmonized Regulation") (SARA Contracts), which are those to which the Community Directive regulating public contracts applies.

The rest of the entities whose ownership is public will not be able to carry out SARA contracts.

Article 70.2 of the consolidated text of the Public Sector Contracts Law")[2]​ establishes that in order to maintain the classification, the maintenance of the economic and financial solvency") and, every three years, that of the technical and professional solvency") of the company must be justified.[3]​.

The legal regime of public contracts. In order to address it, we must distinguish between administrative contracts and private contracts.

They are those signed by a Public Administration, with some specialty, since there are contracts signed by a Public Administration that must be considered private (such as those for artistic creation and interpretation, shows or certain financial services).

They are completely governed by the Public Sector Contracts Law (or, if it is a special administrative contract not classified therein, by its specific regulations), its implementing provisions and by the rest of the administrative law regulations. Only in cases of interpretative gaps should private law be resorted to.

In this sense, we choose to define the contractual concept of the Public Administration as the agreement of two or more parties to create, regulate, modify or extinguish a patrimonial legal relationship, of which at least one of the parties is an entity of the Public Administration.

It should be noted that, according to this definition, it is clear that the distinctive element of the contract is not the fact that the administrative entity that celebrates the contract has special prerogatives in its favor, since it may or may not even condition such prerogative to certain circumstances, but that at least one of the parties that celebrate the contract is a Public Administration.

They are private contracts:

This type of private contracts is where the theory of separable acts has been designed, essential to understand their legal regime. Under the same:

This is important since administrative law grants the Administration a series of prerogatives during contractual execution (unilateral interpretation, unilateral modification, imposition of penalties...) that cease to exist in the private contract. Therefore, the public sector contract cannot be defined as a contract where one of the parties has exorbitant powers, since that can only be predicated of the administrative contract which, as we see, is a subtype of public contract.