In the Philippines, where absolute divorce is not yet recognized under the Civil Code, the dissolution of a marriage is primarily sought through two legal avenues: Annulment of a Voidable Marriage or a Declaration of Absolute Nullity of a Void Marriage. While the public often uses the term "annulment" for both, they are distinct legal concepts governed by the Family Code of the Philippines.

I. Annulment vs. Declaration of Nullity

Before filing, it is crucial to understand which remedy applies to your situation.

Annulment (Article 45): This applies to a "voidable" marriage. The marriage is considered valid until it is set aside by a court decree. The grounds must have existed at the time of the marriage.
Declaration of Absolute Nullity (Articles 35, 36, 37, 38): This applies to a "void" marriage. The marriage is considered non-existent from the beginning (void ab initio). The most common ground cited is Psychological Incapacity (Article 36).

II. Legal Grounds for Filing

Grounds for Annulment (Voidable Marriages)

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

Lack of Parental Consent: If a party was between 18 and 21 years old and the marriage was celebrated without the consent of parents or guardians.
Unsound Mind: Either party was incapable of giving intelligent consent.
Fraud: Consent was obtained through deceptive means (e.g., non-disclosure of a prior conviction, pregnancy by another man, or a sexually transmitted disease).
Force, Intimidation, or Undue Influence: Consent was obtained through threats or violence.
Physical Incapacity: One party is physically incapable of consummating the marriage (impotence), and such incapacity appears to be incurable.
Serious and Incurable STD: One party was afflicted with a sexually transmitted disease found to be serious and incurable.

Grounds for Nullity (Void Marriages)

Psychological Incapacity (Article 36): When a party is psychologically incapacitated to comply with the essential marital obligations.
Absence of Requisites: Lack of a valid marriage license or lack of authority of the solemnizing officer.
Incestuous Marriages: Marriages between ascendants and descendants or siblings.
Bigamous/Polygamous Marriages: Marriages contracted by a person during the subsistence of a previous valid marriage.

III. Essential Requirements for Filing

To initiate the process, the following documents and requirements are generally necessary:

PSA Marriage Certificate: An official copy from the Philippine Statistics Authority.
PSA Birth Certificates: Of the spouses and any common children.
Psychological Evaluation Report: Essential for Article 36 cases. This involves interviews with a clinical psychologist or psychiatrist.
Affidavits of Witnesses: Statements from friends, family, or people who knew the couple and can testify to the breakdown of the marriage.
Proof of Residency: Utility bills or certificates of residency to establish the jurisdiction of the Regional Trial Court (RTC).
Inventory of Assets: If there are properties or debts to be liquidated.

IV. The Legal Procedure: Step-by-Step

The procedure is governed by A.M. No. 02-11-10-SC (Rule on Declaration of Absolute Nullity of Void Marriages and Annulment of Voidable Marriages).

1. Preparation and Filing of the Petition

The petitioner, through counsel, files the verified petition in the Regional Trial Court (RTC) of the province or city where either the petitioner or the respondent has been residing for at least six months prior to the filing.

2. Summons and Answer

The court issues a summons to the respondent. The respondent has 15 days (or 30 days if served by publication) to file an "Answer."

3. Investigation by the Public Prosecutor

If no Answer is filed, or even if one is, the court directs the Public Prosecutor (Fiscal) to investigate whether collusion exists between the parties. The State’s role is to ensure that the parties are not "teaming up" to bypass the law, as the State protects the institution of marriage.

4. Pre-Trial Brief and Conference

The parties submit a Pre-Trial Brief. During the conference, the court explores the possibility of settlement (regarding property and child custody) and simplifies the issues for trial. Note: The marriage itself cannot be the subject of a compromise agreement.

5. The Trial

This is the evidentiary stage where:

The Petitioner testifies.
The Psychologist/Psychiatrist presents findings on psychological incapacity.
Corroborating witnesses provide testimony.
The Respondent may present counter-evidence.

6. Judgment and Decree

If the court finds sufficient evidence, it will render a Decision granting the annulment or nullity. After the decision becomes final (usually after 15 days without an appeal), the court issues the Decree of Annulment/Nullity.

V. Timeline and Estimated Costs

Factor	Typical Estimation
Duration	2 to 5 years (depending on court decongestion and complexity).
Legal Fees	Varies significantly based on the lawyer's expertise and the location.
Psychological Eval	Costs for professional clinical assessment and court appearance.
Filing Fees	Paid to the Clerk of Court upon filing the petition.

VI. Effects of a Final Decree

Status: The parties return to the status of being "single" and can legally remarry.
Legitimacy of Children: Children conceived before the decree of annulment or under Article 36 are generally considered legitimate.
Property Relations: The absolute community of property or conjugal partnership is dissolved and liquidated.
Succession: The right of the spouses to inherit from each other ab intestato (without a will) is revoked.

Important Note: A court decision is not the final step. To be fully effective and allow for remarriage, the Decree must be registered with the Local Civil Registry where the marriage was recorded, the Local Civil Registry of the court, and the Philippine Statistics Authority (PSA).