In short
Naming a substitute means foreseeing that the heir you chose may not become one. Article 1668 allows it in two cases: when the instituted person does not want to or cannot accept the inheritance. And it adds a default rule that saves trouble: unless the testator provides otherwise, a substitution ordered for one of these cases is valid for the other. If you wrote “if my son renounces, let my niece inherit”, the Code understands it also covers your son being unable to accept, unless you say otherwise. Article 1669 resolves the case where the heirs substitute each other: the share of the instituted person who does not become an heir is deferred to the others in proportion to their respective shares; and if there are only two instituted, the share of the one who does not become an heir is deferred entirely to the other. Article 1670 says with what burden the substitute enters: they succeed with the same limitations and modalities of the institution, except when the testator provided differently, or when those limitations were imposed in consideration of the instituted person’s personal attributes. And Article 1671 is the one to memorise, because it settles in a single sentence a clash of three figures: the right of transmission prevails over substitution, and substitution over accretion. The right of transmission is the one in Article 1586: if the called person dies without accepting or repudiating, that right to accept or repudiate passes to their own heirs. So if the heir dies without deciding, their heirs win before the substitute you named; and the substitute wins before the coheirs who would accrete.
What is it?
They are Articles 1668 to 1671 of the Civil Code of 2020: when a substitute may be named in a will, how it is split when the heirs substitute each other, under what conditions the substitute enters, and which figure wins when several compete.
Who can do it?
Anyone drafting a will who wants to foresee a replacement, and any heir, substitute or coheir disputing who gets a vacant share.
Requirements
- The testator may designate a substitute for when the instituted person does not want to or cannot accept the inheritance.Verified against the official source
- Unless provided otherwise, a substitution ordered for one of those cases is valid for the other.Verified against the official source
- If the instituted substitute each other, the vacant share is deferred to the others in proportion to their shares; if there are two, entirely to the other.Verified against the official source
- The substitute succeeds with the same limitations and modalities, unless provided differently or unless they were imposed for the instituted person’s personal attributes.Verified against the official source
- The right of transmission prevails over substitution, and substitution over accretion.Verified against the official source
Documents you need
Cost
Step by step
Step 1: Two cases for the substitute
Article 1668: when the instituted person does not want to accept, or cannot accept.
Step 2: One covers the other by default
The same article: unless the testator provides otherwise, a substitution ordered for one is valid for the other.
Step 3: If they substitute each other
Article 1669: the share of the one who does not become heir is deferred to the others in proportion to their respective shares.
Step 4: And if there are only two
The same article: the share is deferred entirely to the other.
Step 5: The substitute inherits the conditions
Article 1670: they succeed with the same limitations and modalities of the institution.
Step 6: Except in two cases
That the testator provided differently, or that the limitations were imposed for the instituted person’s personal attributes.
Step 7: The order when several figures clash
Article 1671: the right of transmission prevails over substitution, and substitution over accretion.
Step 8: What the right of transmission is
The one in Article 1586: if the called person dies without accepting or repudiating, that right passes to their own heirs. It has its own guide here.
Where to do it
The substitution is written into the will, not processed before any agency. The open will is executed before a notary and the holographic one is handwritten; both forms have their own guide on this site. These four articles set no form, fee or deadline, and none is invented here.
How long it takes
What to do if something goes wrong
If you are writing the will, Article 1668 lets you name a substitute for two cases: the instituted person not wanting to accept, and not being able to. And it spares you writing both, because unless you say otherwise, the substitution you order for one is valid for the other. If you want the opposite — the substitute entering only if the first renounces, but not if they die first — you must say so expressly. If the decedent has died and there is a fight over a vacant share, the article that settles it is 1671, and it settles fast: first the right of transmission, then substitution, and last accretion. That is, if the heir died without accepting or repudiating, their own heirs go ahead of the substitute the testator named. If the instituted substituted each other, Article 1669 divides the vacant share in proportion to the others’ shares, and if there were only two, it gives it entirely to the other. And mind what the substitute inherits: Article 1670 has them enter with the same limitations and modalities, unless the testator said otherwise or those conditions were set for the first one’s personal attributes. The Code does not say what happens if the substitute also cannot or will not accept, nor how many substitutes may be chained, nor what personal attributes are. None of that is filled in here. MiPRFácil does not represent anyone in court and gives no legal advice.
Common mistakes
- Writing the substitution only for renunciation and believing it does not cover inability: Article 1668 extends it unless provided otherwise.
- Wanting to limit it to one case without saying so: it must be expressly provided.
- Splitting the vacant share equally when they substitute each other: Article 1669 splits it in proportion to the shares.
- Forgetting the two-heir rule: the share goes entirely to the other.
- Believing the substitute enters free of conditions: Article 1670 passes them the same limitations and modalities.
- Passing the substitute a condition imposed for the first one’s personal attributes: the same article excludes it.
- Taking for granted the named substitute always wins: Article 1671 puts the right of transmission first.
- Thinking accretion among coheirs goes first: Article 1671 puts it last.
Frequently asked questions
What if the will’s heir dies before the testator?
If you named a substitute, Article 1668 covers it even if you only foresaw renunciation, unless you provided otherwise.
Which wins first, substitution or accretion?
Article 1671 says the right of transmission prevails over substitution, and substitution over accretion.
The heirs substitute each other. How is the vacant share split?
Article 1669 defers it to the others in proportion to their respective shares; if there are only two, entirely to the other.
Does the substitute enter under the same conditions?
Article 1670 says yes, unless the testator provided differently or the conditions were imposed for the instituted person’s personal attributes.
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 11, 2026
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Was this guide helpful?
Did you find out-of-date information?
A will that names no heirs is still valid
Article 1660 of the Civil Code of 2020 says so in one sentence, and 1663 splits in equal parts when no shares were set.
If another heir does not take their share, yours grows and you cannot refuse it
Article 1616 of the Civil Code of 2020 says the right of accretion is irrenunciable, and that it yields to the right of representation when that applies.
Repudiating an inheritance is valid only by public deed or a writing to the court
Article 1583 of the Civil Code of 2020 gives only those two routes. Accepting does admit a private document; repudiating does not.
How to make a will in Puerto Rico
The 2020 Civil Code’s kinds of will, who may execute one, and the rule that changed: with forced heirs you may freely dispose of half.
If the court sets you a term and you do not answer, the inheritance is taken as accepted
Article 1578 of the Civil Code of 2020 lets any interested person request that term 30 days after the delación, and silence does not repudiate: it accepts.
Accepting or repudiating an inheritance cannot be partial, timed or conditional
Article 1573 of the Civil Code of 2020 forbids it, and 1571 adds that acceptance and repudiation are unilateral and irrevocable acts.