In the Philippines, where absolute divorce is not yet legally recognized for non-Muslim citizens, the only ways to sever a marital bond are through Annulment or a Declaration of Nullity of Marriage. While often used interchangeably in casual conversation, these are distinct legal actions under the Family Code of the Philippines.

1. Understanding the Legal Grounds

Before filing, one must identify whether the marriage is void or voidable.

Declaration of Nullity (Void Marriages)

A marriage is "void ab initio" (void from the beginning) if it was never valid. Common grounds under Articles 35, 36, 37, and 38 include:

Psychological Incapacity (Article 36): The most common ground, where one or both parties are unable to comply with essential marital obligations due to a grave psychological condition existing at the time of the marriage.
Absence of Requisites: Lack of a valid marriage license or authority of the solemnizing officer.
Bigamous or Polygamous Marriages: Marrying while a previous marriage is still subsisting.
Incestuous Marriages: Marriages between siblings, or between ascendants and descendants.

Annulment (Voidable Marriages)

A marriage is "voidable" if it is valid until it is set aside by a court. Grounds under Article 45 include:

Lack of Parental Consent: If a party was between 18 and 21 and married without parental consent.
Insanity: Either party was of unsound mind at the time of marriage.
Fraud: Obtaining consent through concealment of a prior conviction, pregnancy by another man, or an STD.
Force, Intimidation, or Undue Influence.
Physical Incapacity: Impotence that is permanent and appears incurable.
Serious Sexually Transmitted Disease: If the disease is existing at the time of marriage and is serious/incurable.

2. The Step-by-Step Legal Process

The procedure for filing is rigorous and requires strict adherence to the Rule on Declaration of Absolute Nullity of Void Marriages and Annulment of Voidable Marriages (A.M. No. 02-11-10-SC).

Step 1: Legal Consultation and Retainer

The petitioner must hire a licensed lawyer. The lawyer will interview the client to determine if there are sufficient legal grounds. At this stage, the lawyer drafts the Petition.

Step 2: Psychological Evaluation

If the ground is Psychological Incapacity (Art. 36), the petitioner usually undergoes an evaluation by a clinical psychologist or psychiatrist. While the Supreme Court (in Tan-Andal v. Andal) ruled that a medical degree is no longer strictly required to prove incapacity, expert testimony remains highly persuasive in establishing that the incapacity is "grave, incurable, and has juridical antecedence."

Step 3: Filing the Petition

The petition is filed in the Regional Trial Court (RTC) of the province or city where the petitioner or the respondent has resided for at least six months prior to the filing.

Step 4: 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."
If no answer is filed, the court does not automatically grant the annulment.

Step 5: Collusion Investigation

The court directs the Public Prosecutor to conduct an investigation to determine if "collusion" exists—meaning, whether the parties fabricated evidence or agreed to the annulment just to get out of the marriage. If collusion is found, the case is dismissed.

Step 6: Pre-Trial Brief and Conference

The parties submit their evidence and list of witnesses. The court may also refer the case to Mediation regarding issues like child custody and property division, though the validity of the marriage itself cannot be mediated.

Step 7: The Trial

The petitioner must present evidence and witnesses (including the psychologist, if applicable). The respondent has the right to cross-examine and present counter-evidence. The Office of the Solicitor General (OSG) often participates to represent the interest of the State in protecting the "inviolability of marriage."

Step 8: Judgment and Decree

If the judge is convinced, a Decision is issued. However, the marriage is not yet officially dissolved. There is a 15-day period to file an appeal. Once the decision becomes "final and executory," the court issues a Decree of Annulment/Nullity.

3. Necessary Documentation

The following documents are typically required for the filing:

NSO/PSA Certified True Copy of the Marriage Contract.
NSO/PSA Certified True Copies of the Birth Certificates of children (if any).
Psychological Evaluation Report (if applicable).
Evidence of residence (e.g., Barangay Certificate, utility bills).
Affidavits of witnesses.

4. Effects of the Court Decision

Feature	Declaration of Nullity (Void)	Annulment (Voidable)
Status of Children	Generally "Illegitimate" (Exception: Art. 36 and 53)	"Legitimate" (if conceived before the decree)
Property Regime	Governed by Co-ownership (Art. 147/148)	Liquidation of Absolute Community/Conjugal Partnership
Right to Remarry	Yes, after registration of the decree	Yes, after registration of the decree
Surname	Woman must revert to maiden name	Woman may revert to maiden name

5. Timeline and Costs

The process is notoriously lengthy and expensive.

Timeline: On average, it takes 2 to 5 years, depending on the court’s docket, the complexity of property issues, and whether the OSG appeals the decision.
Estimated Costs: Total costs can range from PHP 200,000 to PHP 600,000+. This includes:
- Attorney’s fees (Acceptance fees, appearance fees, and pleading fees).
- Psychological expert fees (PHP 30,000 – PHP 80,000).
- Filing fees and publication costs.

6. Important Legal Nuances

The "Tan-Andal" Doctrine: Recent jurisprudence has shifted Psychological Incapacity from a "medical" concept to a "legal" one. It no longer needs to be a clinical personality disorder; it can be proven by ordinary witnesses who can describe the person’s behavior.
No "No-Fault" Annulment: You cannot get an annulment simply because you have "irreconcilable differences" or have been separated for a long time. There must be a specific legal ground proven in court.