In short
Chapter III of Title III of the Civil Code of 2020 fits in two articles. Article 1526 defines: if a person, without just cause, is enriched at another’s expense, they are obliged to indemnify them for the correlative patrimonial decrease in the measure of their own enrichment, whether it comes from obtaining an advantage or from avoiding a harm. Two details of that sentence change the arithmetic. The first is the measure: indemnification is in the measure of the enrichment of the one who gained, not of the loss of the one who lost; if the other gained less than you lost, the cap is their enrichment. The second sits at the end: the enrichment counts the same whether it came from obtaining an advantage or from avoiding a harm, so saving a cost at another’s expense is in. Article 1527 says when the action does not lie, and it is the article that closes the most cases: if the law denies the action; if the law attributes other effects to the enrichment; if the law allows the impoverished party to exercise another action; or if between the parties or interested persons there is a contractual relationship. The last two subsections close the most doors in practice, because they make this a residual action: if you have another route, or if a contract binds you, this chapter is not your path. The Code refers three times to "the law" in a single article without naming one, and this guide names none either. Nor does it define what a just cause is, or say how the enrichment is measured or valued, or set a period to claim.
What is it?
They are Articles 1526 and 1527 of the Civil Code of 2020: when someone must indemnify for having been enriched without just cause at another’s expense, and the four cases where that action does not lie.
Who can do it?
Whoever suffered a patrimonial decrease because another person was enriched without just cause at their expense, under the Puerto Rico Civil Code.
Requirements
- That a person was enriched without just cause at another’s expense.Verified against the official source
- The indemnity is for the correlative patrimonial decrease, in the measure of the enriched party’s own enrichment.Verified against the official source
- The enrichment counts whether it comes from obtaining an advantage or from avoiding a harm.Verified against the official source
- The action does not lie if the law denies it, attributes other effects to the enrichment, allows the impoverished party another action, or if a contractual relationship binds the parties.Verified against the official source
Documents you need
Cost
Step by step
Step 1: What must have happened
Article 1526: that a person, without just cause, be enriched at another’s expense. The Code does not define here what a just cause is, and this guide does not define it for it.
Step 2: How much is owed: the measure is the enrichment
The same article: they are obliged to indemnify them for the correlative patrimonial decrease in the measure of their own enrichment. If the other gained less than you lost, the cap is what they gained.
Step 3: Saving a cost is enrichment too
Closing of 1526: whether it comes from obtaining an advantage or from avoiding a harm. The Code puts both forms on the same footing, and the second is the one overlooked.
Step 4: It is a residual action, and the Code says so
Article 1527 lists four cases where the restitution action does not lie. Read together, they make clear this chapter is used when there is no other route, not as an alternative to those that exist.
Step 5: If the law denies the action or gives it other effects
Subsections (a) and (b): if the law denies the action, or if the law attributes other effects to the enrichment. The article names none of those laws, and we did not read them: none is named here.
Step 6: If another action is available to you
Subsection (c): if the law allows the impoverished party to exercise another action. Having another route closes this one. It is one of the two subsections that leaves the most cases out.
Step 7: And if a contract binds you
Subsection (d): if between the parties or interested persons there is a contractual relationship. Note the article says "parties or interested persons", not only the two directly opposed.
Step 8: What these two articles do not carry
They do not define just cause, name none of the laws they refer to three times, do not say how the enrichment is measured or valued, set no period to claim and name no fee. None of that is here.
Where to do it
The Code names no agency for this chapter. The restitution action is decided by the Court of First Instance. Subsections (a), (b) and (c) of Article 1527 refer to laws the Code does not name.
How long it takes
What to do if something goes wrong
If a contract binds you and the other party, Article 1527(d) closes this action and what applies are that contract’s rules, with their own guides on this site. If what happened is that you paid something you did not owe, that is the chapter on payment of what is not owed, with separate guides. If someone managed an affair of yours uninvited, that is the chapter on management of another’s affairs. If yours is the crime of illicit enrichment by a public official, that is another subject with its own guide. These two articles do not define just cause, do not name the laws they refer to, and set no period. MiPRFácil does not represent anyone in court and gives no legal advice.
Common mistakes
- Claiming unjust enrichment where a contractual relationship binds the parties.
- Using this action while another is available: subsection (c) closes it.
- Measuring the claim by what you lost: the article measures by what the other gained.
- Overlooking that avoiding a harm counts as enrichment.
- Forgetting that subsection (d) speaks of parties or interested persons, not only the two directly opposed.
- Documenting only your own loss and not the other’s enrichment.
- Looking in these articles for the claiming period: they fix none.
- Confusing this civil figure with the crime of illicit enrichment by a public official.
Frequently asked questions
How much can I claim?
Article 1526 requires indemnifying the correlative patrimonial decrease in the measure of the enriched party’s own enrichment. That enrichment is the cap.
The other person gained nothing, they just saved a cost. Does that count?
Article 1526 says the enrichment counts whether it comes from obtaining an advantage or from avoiding a harm.
We have a signed contract. Can I use this action?
Article 1527(d) says the restitution action does not lie if between the parties or interested persons there is a contractual relationship.
How long do I have to claim?
These two articles set no period. The Code does not say here and this guide does not supply it.
Official sources
These are the government pages this guide is based on.
- Poder Judicial de Puerto Rico
Poder Judicial
bvirtualogp.pr.gov
Last verified
September 10, 2026
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Did you find out-of-date information?
You paid what you did not owe: you need not prove you were mistaken
Article 1520 gives the right to demand restitution of what was paid without legal cause, and says expressly it does not depend on a mistake.
You received a payment not yours: good faith changes what you return
Article 1522 makes a bad-faith recipient pay interest or fruits; 1523 limits the good-faith one to the extent they were enriched.
You took on someone else’s affair uninvited: you cannot just drop it
Article 1517 requires the manager to notify without delay and to continue until the interested party can take over, ratify or entrust it to another.
You managed another’s affair: expenses are repaid up to the benefit it gave
Article 1519 makes the interested party who benefits reimburse expenses and losses up to the benefit received, even without having ratified.
What an obligation is and where it comes from
Six sources, and the list stays open. Whoever performs knowing they were not bound cannot demand it back.
Illicit enrichment: what it is and why it now carries restitution
Act 155-2026 makes restitution mandatory when the official obtains the benefit. Three years for using the information, eight for profiting.