In the Philippine legal system, the sanctity of marriage is protected by robust property laws. When a husband diverts marital funds to acquire property and registers it under the name of a mistress, the law does not leave the legitimate wife empty-handed. Through the lens of the Family Code and the Civil Code, the registered "owner" (the mistress) may often be revealed as a mere trustee for the benefit of the conjugal partnership.

1. The Presumption of Conjugal Ownership

The foundational principle in Philippine law is that all property acquired during the marriage is presumed to be conjugal, regardless of whether the title is in the name of only one spouse (Article 116, Family Code).

If a husband uses money earned during the marriage to buy a house for his mistress, that money belongs to the Absolute Community of Property (ACP) or the Conjugal Partnership of Gains (CPG). Because the funds used were conjugal, the property acquired with those funds is also conjugal, even if the husband deliberately puts the mistress’s name on the Transfer Certificate of Title (TCT).

2. The Concept of Implied Trust

When property is acquired through funds provided by one party but the title is placed in the name of another, an implied trust is created by operation of law (Article 1448, Civil Code).

The Scenario: The husband pays the purchase price.
The Registration: The title is issued to the mistress.
The Legal Effect: The mistress is considered a "trustee" holding the property in trust for the real owner—the conjugal partnership. The legitimate wife can file an action for Reconveyance, asking the court to order the mistress to transfer the title back to the names of the legal spouses.

3. The Prohibition on Donations Between Spouses (and Paramours)

The law is particularly strict regarding gifts. Under Article 87 of the Family Code, donations between spouses during the marriage are void (except for moderate gifts on family occasions).

By extension, Article 739 of the Civil Code declares donations made between persons guilty of adultery or concubinage at the time of the donation to be void.

A husband cannot "gift" a property to a mistress.
Even if the husband claims he "gave" her the money to buy the property, the donation is void from the beginning (void ab initio).
Since the donation is void, the property never legally left the husband's estate/conjugal partnership.

4. The Problem of the "Torrens System"

A common defense used by mistresses is the Indefeasibility of the Torrens Title. They argue that because their name is on the TCT, they are the absolute owners.

However, the Supreme Court has consistently ruled that the Torrens system is not a shield for fraud. If it can be proven that the funds used were conjugal and the registration was a scheme to defraud the legitimate wife, the court can "pierce" the certificate and look at the source of the funds. The registration of the property in the mistress's name does not make her the owner if the acquisition had no valid legal basis (i.e., a void donation).

5. Right to Recover and Remedies

A legitimate wife has several legal avenues to recover these properties:

Action for Reconveyance

This is the primary remedy. The wife sues to show that the mistress is not the true owner and that the property should be reconveyed to the conjugal partnership.

Declaration of Nullity of Title/Deed of Sale

If the husband forged the wife's signature or used a "simulated sale" (a fake sale) to transfer property to the mistress, the wife can move to declare these documents null and void. Under Article 124 of the Family Code, the administration of conjugal property belongs to both spouses. Any disposition (sale or mortgage) without the written consent of the other spouse is void.

Criminal Prosecution

While not a direct property recovery method, filing a criminal case for Concubinage (against the husband and mistress) or Violation of RA 9262 (Anti-Violence Against Women and Their Children Act) for economic abuse can provide significant leverage in settlement negotiations and serves as evidence of the illicit relationship.

6. Burden of Proof

To succeed, the legitimate wife must provide "clear and convincing evidence" of the following:

The Marriage: A valid marriage certificate.
Source of Funds: Evidence that the husband provided the money (e.g., bank transfers, checks, or proof that the mistress had no financial capacity to purchase the property at that time).
The Relationship: Evidence of the illicit affair to trigger the prohibition on donations under Article 739.

Summary Table: Rights and Legal Basis

Legal Basis	Core Principle	Application to Mistress
Art. 116, Family Code	Presumption of Conjugal Property	Property bought with marital funds belongs to the wife & husband.
Art. 87, Family Code	Prohibition of Donations	Husband cannot validly give property/money to a mistress.
Art. 1448, Civil Code	Implied Trust	Mistress is a mere "trustee," not the owner.
Art. 124, Family Code	Joint Administration	Sale/Transfer without wife's consent is void.