Civil contracts: exchange, assignment of credits, mandate, deposit and commodatum

Exchange (articles 1538 to 1541 of the Código Civil): each party is obliged to give one thing to receive another. Money can intervene as compensation (exchange with return). In what is not foreseen in its title, it is governed by the rules of sale and purchase (art. 1541).

Assignment of credits (articles 1526 to 1536): the creditor (assignor) transfers to a third party (assignee) a credit owed to them. The assignment includes accessory rights such as surety, mortgage or pledge (art. 1528). The assignor is liable for the existence and legitimacy of the credit, but not for the solvency of the debtor unless agreed (art. 1529). The debtor who pays before knowing of the assignment is released (art. 1527).

Mandate (articles 1709 to 1739): a person (mandatory) is obliged to provide a service or do something on behalf of or at the request of another (mandator). It is presumed free of charge unless the mandatory is professionally dedicated to it (art. 1711). To compromise, alienate, mortgage or any act of strict ownership, an express mandate is required (art. 1713).

Deposit (articles 1758 to 1789): one receives another's movable property with the obligation to keep it and return it when asked (art. 1758). It is free of charge unless agreed otherwise (art. 1760) and only falls on movable things (art. 1761). The depositary cannot use the thing without the express permission of the depositor (art. 1767).

Commodatum or loan for use (articles 1740 to 1752): one party delivers a non-fungible thing free of charge for the other to use for a certain time and return it. It is essentially free of charge (art. 1740): if the one who uses the thing pays any emolument, it ceases to be a commodatum (art. 1741). The bailor retains ownership and the bailee acquires the use, not the fruits.

Surety (articles 1822 to 1856): the guarantor is obliged to pay or comply for a third party in case the latter does not do so (art. 1822). It is not presumed: it must be express (art. 1827). The guarantor has the benefit of excussion, that is, they cannot be forced to pay until the debtor's assets are pursued (art. 1830), unless waived or in a joint and several surety.

By what they transfer: exchange transfers the ownership of one thing in return for another; assignment of credits transfers a collection right; commodatum and deposit do not transfer ownership (only the use or safekeeping of the thing); mandate transfers nothing, it entrusts an action; surety transfers nothing, it guarantees another's debt.

By their free or onerous nature: exchange is always onerous; deposit and mandate are presumed free unless agreed otherwise; commodatum is essentially free by definition; assignment of credits and surety can be free or onerous.

2 frequent confusions: deposit versus commodatum (in a deposit you keep a thing and cannot use it; in a commodatum the thing is lent to you precisely to use it) and commodatum versus lease (commodatum is free; as soon as there is rent it is a rental). The comparative table at the end summarises the latter.

Common to all: complete identification of the parties, precise description of the object (the thing, the credit, the task or the guaranteed debt), free or onerous nature and consideration if any, date, and signature. The private contract with a certain date protects against third parties (arts. 1218 and 1227).

Exchange: description and registry identification of each asset, monetary compensation if any, warranty against eviction (arts. 1539 and 1540) and warranty against hidden defects (which arrives by the referral of art. 1541 to the rules of sale and purchase, arts. 1484 and following). Assignment of credits: assigned credit and its accessories, price, scope of the assignor's liability and the convenience of notifying the debtor.

Mandate: whether it is general or special and the exact scope of the powers (with express mention for acts of strict ownership, art. 1713), remuneration and rendering of accounts. Deposit and commodatum: description of the thing, duration, form and time of return, and state in which it is delivered and returned.

Surety: guaranteed obligation, maximum amount, whether it is simple or joint and several, and whether the guarantor waives the benefits of excussion, division and order. These waivers completely change the guarantor's position, which is why Managora drafts them expressly and clearly.

For their validity, these contracts do not require a special form: the freedom of form of article 1278 of the Código Civil applies, so a signed private document is fully valid and binding between the parties.

The public deed before a notario (Spanish notary public) is necessary or highly recommended when the contract involves real estate, in order to register it in the Registro de la Propiedad (Property Registry) and provide it with a certain date against third parties (art. 1280). The mandate for acts that must be recorded in a public document (for example, a power of attorney to sell a property) is also granted in a deed.

Taxes: the exchange is taxed by Transfer Tax (modelo 600, between individuals it taxes both transfers) or by VAT when the parties are entrepreneurs, and for real estate the minimum base is the Catastro (Cadastre) reference value. The assignment of credits has a more variable tax treatment: many onerous assignments are not subject or exempt (for example, due to the exemptions for credits and financial operations of art. 45 of the texto refundido del ITP y AJD (consolidated text of the ITP and AJD)), so not every onerous assignment is taxed by Transfer Tax. Free commodatum and deposit are not taxed by Transfer Tax, but a hidden liberality can have effects on IRPF (Spanish personal income tax) or Gift Tax. Managora analyses each case, calculates what corresponds and indicates the amount in the procedure file.

The Código Civil (Real Decreto of 24 July 1889) remains the current regulation for the 6 contracts as of 17 July 2026. There is no substantive reform in 2026 of exchange, assignment of credits, deposit, commodatum or surety.

The most relevant live change affects the mandate: Ley 8/2021 (the Spanish Act on support for persons with disabilities), of 2 June, reformed article 1732. The mandate is no longer automatically extinguished by the disability of the mandator, and preventive powers of attorney are consolidated, which subsist or are activated if the mandator loses their capacity. It is a key tool to plan the management of your affairs.

In tax matters, the Catastro (Cadastre) reference value (Ley 11/2021, in force since 1 January 2022) continues to set the minimum taxable base for Transfer Tax in the exchange of real estate.