Short answer. No. Article 1213 of the Civil Code states plainly that a solidary creditor cannot assign their rights without the consent of the other solidary creditors. Selling your right to collect to a third party without that consent is not permitted — you need all the others to agree first.
What the law says
A solidary creditor cannot assign his rights without the consent of the others.
Civil Code, Article 1213 — Assignment by a Solidary Creditor. Read the full provision →
Why solidary creditors cannot act alone on assignment
In a solidary obligation, each creditor is entitled to demand the entire debt from the debtor. That right is powerful precisely because it belongs to the group — any one creditor can enforce the full obligation. But that same collective character is why assignment is restricted. If one solidary creditor could assign their share to a stranger without the others' agreement, the debtor and the remaining creditors would suddenly be dealing with someone they never agreed to have involved. Article 1213 prevents that outcome by requiring the consent of all the other solidary creditors before any assignment can take place.
The distinction between collecting and assigning
There is an important distinction here. A solidary creditor can collect the entire debt on their own — that is one of the core features of solidarity. But assigning their right — transferring it to a third person in exchange for something — is a different act. Collection benefits everyone in the solidarity; assignment substitutes a new party for one creditor without the others' input. The law treats these differently. You may demand payment from the debtor without asking your co-creditors. You may not sell that right to someone else without them.
What happens if you assign without consent
An assignment made by one solidary creditor without the consent of the others lacks legal validity to bind the remaining creditors. The purported assignee takes on an uncertain right, because the transfer itself was made in violation of a statutory rule that exists to protect the other solidary creditors. The other creditors could contest the assignment, and the debtor might face conflicting demands if the assignee and the remaining solidary creditors both attempt to collect. Getting consent before assigning avoids all of this. It also signals good faith to any potential buyer — a right transferred with proper consent is far cleaner.
How to get the consent you need
Obtaining the consent of your co-creditors means communicating your intention to assign, identifying the proposed assignee, and getting each co-creditor's agreement to the transfer. There is no prescribed form for this in Article 1213, but written consent is strongly advisable — you want a clear record that the others agreed before you complete the assignment. If any of them refuse, the assignment cannot proceed without them on board. If you are considering assigning your rights and one co-creditor is being unreasonable or uncooperative, a lawyer can help you assess whether any other avenues are available to you.