In the Philippines, marriage is legally defined as a "special contract of permanent union" between a man and a woman. Because the country does not currently recognize absolute divorce (except under the Code of Muslim Personal Laws), the primary legal routes to exit a failed marriage are Declaration of Nullity and Annulment.

While these terms are often used interchangeably in casual conversation, they represent distinct legal concepts under the Family Code of the Philippines.

1. Annulment vs. Declaration of Nullity

Declaration of Nullity (Article 35, 36, 37, 38): Applies to marriages that were void from the beginning (void ab initio). In the eyes of the law, the marriage never existed because it lacked an essential or formal requisite (e.g., absence of a license, bigamous marriages, or psychological incapacity).
Annulment (Article 45): Applies to marriages that are voidable. These marriages are considered valid until they are set aside by a court decree. The defect in the marriage existed at the time of the celebration but is not considered severe enough to make the union non-existent from the start.

2. Grounds for Annulment (Voidable Marriages)

Under Article 45 of the Family Code, a marriage may be annulled for any of the following reasons existing at the time of the marriage:

Lack of Parental Consent: If either party was between 18 and 21 years old and the marriage was solemnized without the consent of the parents or guardians, unless the party freely cohabited with the other after reaching the age of 21.
Insanity: If either party was of unsound mind, unless such party freely cohabited with the other after coming to reason.
Fraud: If the consent of either party was obtained through fraud. Legally recognized fraud is limited to:
Non-disclosure of a previous conviction of a crime involving moral turpitude.
Concealment of pregnancy by another man.
Concealment of a sexually transmitted disease (STD) existing at the time of marriage.
Concealment of drug addiction, habitual alcoholism, or homosexuality/lesbianism.
Force, Intimidation, or Undue Influence: If consent was obtained through external pressure that vitiated free will.
Physical Incapacity (Impotency): If either party is physically incapable of consummating the marriage (inability to have sexual intercourse) and such incapacity appears to be incurable.
Serious and Incurable Sexually Transmitted Disease: If either party was found to have an STD that is serious and appears to be incurable.

3. The Ground of Psychological Incapacity (Article 36)

Though technically a ground for Declaration of Nullity, Article 36 is the most common route for ending a marriage in the Philippines. It refers to a party who is "mentally or psychically" incapable of complying with the essential marital obligations (e.g., mutual love, respect, support, and fidelity).

Key characteristics of Psychological Incapacity:

Gravity: The incapacity must be serious.
Juridical Antecedence: It must have existed at the time of the marriage ceremony (even if it manifested only later).
Incurability: It must be incurable or, at the very least, beyond the capacity of the party to resolve.

*Note: In the landmark case of Tan-Andal v. Andal (2021), the Supreme Court clarified that psychological incapacity is not a medical/clinical concept but a legal one. It does not require a psychiatrist’s examination of the respondent, though expert testimony remains helpful.*

4. Procedural Requirements

The process for filing an Annulment or Declaration of Nullity is governed by the Rule on Declaration of Absolute Nullity of Void Marriages and Annulment of Voidable Marriages (A.M. No. 02-11-10-SC).

Filing the Petition: The petition must be filed in the Regional Trial Court (Family Court) of the province or city where the petitioner or respondent has been residing for at least six months.
Summons: The court issues a summons to the respondent. If the respondent cannot be located, service by publication may be allowed.
Collusion Investigation: The Public Prosecutor is mandated to conduct an investigation to ensure that the parties are not conniving or "faking" the grounds to get a "quick" annulment.
Pre-Trial and Trial: The petitioner must present evidence, including witnesses and, frequently, psychological evaluations.
Decree of Annulment: If the judge is satisfied, a Decision is rendered. Once final, a Decree of Annulment is issued.

5. Essential Documentation

To initiate the process, the following documents are typically required:

PSA-issued Marriage Certificate.
PSA-issued Birth Certificates of children (if any).
Evidence of residency (e.g., Barangay Certificate, utility bills).
Psychological Evaluation Report (standard in Article 36 cases).
List of common properties and assets for partition.

6. Legal Effects of Annulment

Once the decree is issued and registered with the Local Civil Registrar:

Status: The parties are restored to the status of being single and can legally remarry.
Children: Children conceived or born before the decree are generally considered legitimate (in Article 36 and Article 45 cases). Custody is usually determined based on the "Best Interest of the Child" rule.
Property: The absolute community of property or conjugal partnership is dissolved and liquidated.
Donations: Donations propter nuptias (gifts given by reason of marriage) may be revoked at the instance of the innocent spouse.