Here’s a clear, practice-oriented explainer tailored to the Philippines. It covers definitions, grounds, timelines, evidence, procedure, and after-effects—plus quick checklists and a side-by-side comparison. (This is general information, not legal advice.)

What each remedy is (and isn’t)

Declaration of Nullity (for a void marriage) Says the marriage was never valid from the start (e.g., bigamy, no license, parties below 18, psychological incapacity). It ends the legal status as spouses because the law treats the marriage as void ab initio.
Annulment (of a voidable marriage) Says the marriage was valid at the start but defective (e.g., consent issues, incurable impotence, serious STD). It’s valid until annulled by final judgment.
Legal Separation Keeps the marriage intact (no freedom to remarry) but authorizes spouses to live apart and severs property relations. It’s fault-based (e.g., violence, infidelity, abandonment).

Divorce (with freedom to remarry) remains generally unavailable under civil law in the Philippines (exceptions exist for certain foreign divorces under Art. 26[2] and for Muslims under special laws).

Grounds, filing deadlines, and who can file

A. Declaration of Nullity (void marriages)

Typical grounds (illustrative, not exhaustive):

Either party below 18 at the time of marriage.
No marriage license (unless covered by a narrow statutory exception).
Unauthorized solemnizing officer (no good-faith belief in authority).
Bigamous/polygamous marriage (subject to limited presumptive-death rules).
Psychological incapacity (Art. 36).
Incestuous or marriages void for public policy (certain degrees of relationship).
Mistake in identity of a spouse.

Prescriptive period: Generally none (void marriages are imprescriptible).

Who files: Any spouse with standing (and in some instances, the State may intervene).

B. Annulment (voidable marriages)

Grounds (Art. 45, summarized) & filing deadlines (Art. 47):

Lack of parental consent (party was 18–21): file within 5 years after turning 21.
Insanity: by the sane spouse before regaining sanity; by a relative/guardian if continuous insanity.
Fraud (material deception inducing consent): file within 5 years from discovery.
Force, intimidation, undue influence: file within 5 years from cessation.
Incurable physical incapacity to consummate (impotence): file within 5 years from marriage.
Serious, incurable sexually transmissible disease existing at marriage: file within 5 years from marriage.

Who files: The injured spouse (or guardian/relative where the law allows).

C. Legal Separation

Grounds (Art. 55, summarized):

Repeated physical violence or grossly abusive conduct.
Violence or moral pressure to compel change of religion or political affiliation.
Attempt to corrupt or induce into prostitution.
Final criminal conviction of a crime with >6 years’ imprisonment.
Drug addiction or habitual alcoholism.
Homosexuality/lesbianism (understood as marital breach in jurisprudence).
Bigamy (contracting a bigamous marriage).
Sexual infidelity or perversion.
Attempt on the life of the petitioner.
Abandonment without just cause for >1 year.

Prescriptive period: File within 5 years from the occurrence of the cause.

Who files: The innocent (non-offending) spouse.

What courts look for (evidence & practical notes)

Family Court (RTC) has jurisdiction. Venue: typically where the petitioner resides (or respondent, depending on circumstances).
A Public Prosecutor must investigate collusion and report to the court. The OSG (for nullity/annulment) represents the State.
Psychological incapacity cases are jurisprudence-heavy: it must be grave, antecedent, and incurable as it relates to essential marital obligations. A psychological report is common though not strictly mandatory; testimony must tie traits to incapacity at the time of marriage.
Legal separation has a mandatory 6-month cooling-off period from filing (court suspends trial to encourage reconciliation), but courts may issue provisional relief (e.g., protection orders, support, custody, injunctions).
Evidence often includes: marriage certificate, birth certificates of children, medical/psychological reports, police/barangay blotters, messages/records, photos, criminal judgments, affidavits, financials.

Effects after judgment (status, kids, names, property, succession)

Marital status & ability to remarry

Declaration of Nullity: Marriage treated as never valid; parties are free to remarry after entry of judgment and civil registry annotation.
Annulment: Marriage set aside; parties free to remarry after finality and registration/annotation.
Legal Separation: Still married; cannot remarry.

Children’s status

Annulment (voidable marriage): Children remain legitimate.
Void marriage: Children are generally illegitimate, except where the law expressly preserves legitimacy (e.g., psychological incapacity under Art. 36—children conceived or born before the judgment are treated as legitimate by statute).
Regardless of the remedy, support and parental authority/custody are determined by the best interests of the child.

Surnames

After nullity/annulment, a wife may resume her maiden name (and records are annotated).
In legal separation, the wife may typically continue using the husband’s surname unless the court orders otherwise (resumption of maiden name may be allowed depending on circumstances).

Property relations (very important differences)

If there was a valid marriage later dissolved (annulment or legal separation):

Community/Conjugal property is dissolved and liquidated.
Forfeiture rules may apply to the offending spouse’s share of net profits in favor of common children (or the innocent spouse, absent children).
Creditors are paid; remaining assets are partitioned.

If the marriage was void from the start (declaration of nullity):

Property falls under co-ownership rules (Arts. 147/148), which depend on whether the parties were both in good faith and whether either was disqualified to marry:
- Art. 147 (both free to marry; good faith): Each gets what he/she actually contributed to acquisitions; wages/salaries are presumed jointly owned; bad-faith party forfeits share in certain cases.
- Art. 148 (at least one party disqualified, e.g., bigamy/adultery): Only actual proven contributions are credited; shares of the guilty may be forfeited in favor of common children/innocent spouse (as the law/jurisprudence provide).

Inheritance rights between spouses

Annulment/nullity: Spouses cease to be compulsory heirs of each other from finality; wills may be affected by operation of law.
Legal separation: The offending spouse is disqualified from inheriting intestate from the innocent spouse and testamentary provisions in favor of the offending spouse are revoked by law (effects under Art. 63). The innocent spouse remains a compulsory heir of the offending spouse unless otherwise barred by law.

Support & custody

Support obligations to children remain.
In legal separation, custody of minors is generally awarded to the innocent parent, subject to the best-interests standard (and special laws like the Anti-VAWC Act).
Courts issue provisional orders for support, custody/visitation, exclusive use of the home, protection orders, etc.

Civil registry & ID records

Final judgments must be recorded and annotated with the Local Civil Registry and the Philippine Statistics Authority (PSA). No effective change of civil status for public purposes occurs until annotation is done.

Procedure at a glance (annulment & nullity vs legal separation)

Common preliminaries

Consult counsel; gather documents & witnesses.
File verified petition in the proper Family Court; pay fees.
Prosecutor investigates collusion; OSG participates in annulment/nullity.
Provisional relief (support, custody, residence, protection).

Annulment/Nullity 5) Pre-trial; issues are narrowed; mediation (where appropriate). 6) Trial (petitioner’s evidence, possibly expert testimony, cross-exam, rebuttal). 7) Decision; if granted, finality after lapse of appeal period. 8) Entry of judgment; PSA annotation; then exercise right to remarry.

Legal Separation 5) Mandatory 6-month cooling-off (trial suspended except urgent relief). 6) Trial (prove a ground; respond to defenses like condonation, recrimination). 7) Decision; liquidation of property; custody/support orders; no freedom to remarry. 8) Post-judgment annotation at the civil registry.

Defenses and bars you might encounter

Condonation/forgiveness, recrimination (both spouses at fault), connivance, or collusion can bar legal separation.
Ratification can bar certain annulment grounds (e.g., voluntary cohabitation after force/intimidation ceased; cohabitation after discovery of fraud).
Laches/prescription bars annulment claims with expired filing windows.
In nullity, prescription is typically not an issue, but estoppel or bad faith can affect property claims.

Choosing the right path (quick decision aid)

You want freedom to remarry → Explore Declaration of Nullity (if marriage was void) or Annulment (if voidable).
You do NOT want to dissolve the marriage but must live apart and protect assets/children → Consider Legal Separation.
Your main issue is property disentanglement and safety → Legal Separation can be faster than a contested annulment/nullity in some situations because you don’t have to prove the marriage is void/voidable, only a qualifying marital offense—but you cannot remarry.
Your marriage likely suffered from consent defects at the start (fraud, intimidation, impotence, serious STD) → Annulment (watch the strict deadlines).
Your marriage likely falls into a “never valid” bucket (bigamy, no license, psychological incapacity, below 18) → Declaration of Nullity.

Practical checklists

Basic documents to prepare

PSA-issued Marriage Certificate (and Advisory on Marriages if relevant).
Birth Certificates of children.
IDs, proof of residence (venue).
Evidence: medical/psych reports, messages, financials, police/barangay records, photographs, witnesses, criminal case records (if any).
Property records: titles, bank statements, business docs, inventories.

If safety is a concern

Seek protection orders (e.g., under the Anti-VAWC Act), document incidents, and coordinate with counsel and authorities for shelter, custody, and support measures.

After you win the case

Obtain entry of judgment and final certificate of finality.
Cause PSA annotation (marriage certificate and related records).
Notify banks, employers, schools, and update beneficiaries and ID records as applicable.
For property: finalize liquidation and transfers; settle taxes (CGT/DST if applicable), and creditor claims.

Side-by-side summary

Feature	Declaration of Nullity (Void)	Annulment (Voidable)	Legal Separation
Marriage status	Never valid	Valid until annulled	Still valid
Freedom to remarry	Yes (after finality & PSA annotation)	Yes (after finality & PSA annotation)	No
Typical grounds	Bigamy, no license, <18, data-preserve-html-node="true" psych. incapacity, incest/public policy, mistake in identity	Lack of parental consent (18–21), insanity, fraud, force/intimidation, incurable impotence, serious incurable STD	Violence, infidelity, abandonment (>1 yr), drug addiction, bigamy, attempt on life, etc.
Deadlines	Generally none	Strict (varies by ground)	5 years from cause
Children’s status	Generally illegitimate, except those conceived/born before judgment in Art. 36 cases (legitimate)	Legitimate	N/A (marriage continues)
Property regime	Co-ownership rules (Arts. 147/148)	Liquidate ACP/CPG; possible forfeiture vs. offending spouse	Liquidate ACP/CPG; forfeiture vs. offending spouse
State participation	Prosecutor & OSG	Prosecutor & OSG	Prosecutor (no OSG party role like in nullity/annulment)
Cooling-off	N/A	N/A	6 months (trial suspended; urgent relief allowed)

Final notes

Expect multiple hearings, strict technical rules, and appeal possibilities.
The label you choose affects children’s status, property, and succession—pick carefully.
Always align your plan with safety, finances, and the timeline you can realistically manage.

If you’d like, tell me your top goals (remarrying, property protection, safety, child custody) and any key facts (e.g., bigamy, no license, violence), and I’ll map them to the most fitting remedy and a tailored document/evidence plan.