Short answer. Yes. Article 905 voids any renunciation of a future legitime, letting you claim your full share upon your parent's death, but requires you to bring to collation whatever you already received under that void renunciation. You cannot keep both the earlier payment and your untouched full legitime.
What the law says
Every renunciation or compromise as regards a future legitime between the person owing it and his compulsory heirs is void, and the latter may claim the same upon the death of the former; but they must bring to collation whatever they may have received by virtue of the renunciation or compromise.
Civil Code, Article 905 — Renunciation Of Future Legitime. Read the full provision →
The renunciation itself is void, and your right to the legitime survives it
Article 905 does not leave any room for a compulsory heir to sign away a share of an estate that has not yet opened. It states that "every renunciation or compromise as regards a future legitime between the person owing it and his compulsory heirs is void, and the latter may claim the same upon the death of the former." Because a legitime only becomes a concrete, existing right when the person who owes it dies, any earlier attempt to renounce it in advance simply has no legal effect, and you remain entitled to claim your full legitime once your parent passes away.
But you cannot pretend the earlier payment never happened
The same article balances that protection with an obligation of fairness. It continues: "but they must bring to collation whatever they may have received by virtue of the renunciation or compromise." Collation means the value of what you already received gets added back into the accounting of the estate and credited against your share, so that you are not paid twice for the same legitime — once through the earlier, void arrangement, and again in full afterward.
How this plays out in practice
When the estate is eventually settled, whatever money or property you received under the void renunciation is treated as an advance against your legitime rather than as a separate, additional benefit. Your final share is calculated on the full legitime you are entitled to, then reduced by the value already advanced to you, so you ultimately receive the difference rather than the full share on top of what you were already given.
Why the law strikes this particular balance
This approach protects compulsory heirs from being pressured or persuaded into signing away rights to an inheritance that has not yet vested, while also preventing an heir from using that same protection to collect the same value twice. The renunciation cannot bind you to give up your legitime, but fairness to the other heirs and to the estate as a whole requires that what you already received be accounted for rather than ignored.