Practical legal information for the Philippines. This is not a substitute for tailored advice from counsel on your specific facts.

1) Big picture

To make a father legally answer a petition for support, the court must first acquire jurisdiction over his person, which ordinarily requires valid service of summons. When the father’s whereabouts are unknown, the Rules of Court still allow service—but only after you prove diligent efforts to locate him and obtain the court’s leave for special modes of service.

Support claims are civil actions governed by the Family Code (duty to support) and the Rules of Court (procedure). Family Courts have exclusive original jurisdiction over petitions for support; venue is generally where the petitioner (child, represented by the mother/guardian) resides.

2) Before you file (and while the case is pending): build your “diligent search” record

Courts will not authorize publication or other extraordinary service unless you show specific, concrete efforts to find the respondent. Create a paper trail:

Ask relatives, neighbors, barangay officials of the last known address; get written certifications when possible.
Check the last employer (HR will rarely disclose without authority, but a subpoena can later be sought; still, record the attempt).
Contact known affiliations: school alumni office, professional groups, motorcycle/car clubs, homeowners’ association, parish/church.
Send demand letters to the last known address and known email accounts; keep registry receipts, returned envelopes, and email headers.
Call/message known mobile numbers and social media; keep screenshots and call logs.
Barangay records: obtain a Certificate of Residency/Non-Residency or Brgy. Certification of Attempts to Locate.
Government databases (SSS, PhilHealth, Pag-IBIG, LTO): you generally need a court subpoena to compel disclosure; note your attempts for later motion practice.
Police blotter if there are abandonment issues (optional but sometimes persuasive).

These efforts should be laid out in a detailed, notarized “Affidavit of Diligent Search and Inquiry.” Vague claims like “we looked for him but he can’t be found” are not enough.

3) Filing the case

Court: Family Court (Regional Trial Court designated as such).
Parties: The child, represented by the mother or legal guardian, as petitioner; the father as respondent.
Cause of action: Support (initial, increased, or enforced). You may also claim arrears.
Provisional relief: Move for support pendente lite (temporary support while the case is pending) under the Rules of Court, supported by the child’s needs and the father’s means (or best available evidence thereof).

Tip: If paternity is disputed, you may pair the petition with a motion for DNA testing or proofs of filiation (birth certificate, acknowledgment, communications, financial remittances, etc.). This does not block service; it simply frames the issues.

4) The hierarchy of serving summons when the address is unknown

A) Personal service (default)

If you later discover a current residence or workplace, the sheriff/process server must first attempt personal service there.

B) Substituted service (resident but evasive)

When the respondent resides in the Philippines but cannot be personally served within a reasonable time despite efforts, the court may allow substituted service, e.g., leaving the summons:

at the respondent’s residence with a person of suitable age and discretion residing therein, or
at the respondent’s office with a competent person in charge.

You (or the sheriff) must document dates, times, and the identities of persons spoken to and why personal service failed.

C) Service by electronic means (with leave of court)

On motion and after showing diligent efforts, courts may authorize service by email, social media accounts, or other electronic platforms reasonably believed to be used by the respondent. Provide evidence that the account is his (e.g., prior correspondence, posts, profile links).

D) Service by publication (resident with unknown identity/whereabouts)

If the father is a resident of the Philippines but his whereabouts are unknown, the court may, with leave, direct publication of the summons in a newspaper of general circulation (once a week for a prescribed period) and require additional steps (e.g., registered mail to last known address, email, or posting at the courthouse/barangay hall). Your Affidavit of Diligent Search is crucial here.

Publication is not a shortcut. Courts expect exhaustive pre-publication efforts and will invalidate service if the record shows mere perfunctory attempts.

E) Extraterritorial service (non-resident or abroad)

If the father is not residing in the Philippines or is abroad, seek leave of court for extraterritorial service. Courts can authorize:

personal service abroad if feasible,
publication,
electronic service (email/social media),
transmission through DFA/consular channels, or
any manner the court deems sufficient and consistent with due process and the foreign state’s laws.

Support claims are typically in personam (against the person), so the chosen mode must be reasonably calculated to give actual notice.

5) What to put in your Motion for Leave to Serve by Special Means

Factual narrative of diligent search (attach your Affidavit and exhibits).
Prayer specifying the requested mode(s): substituted, email, messenger app, publication, courier, and combined measures.
Proposed order the judge can adopt, including precise steps (e.g., which email, which account handle, which newspaper, publication dates, and simultaneous registered mail to last known address).
Proof plan: how you will prove completion (affidavit of server, registry receipts, screenshots with timestamps, publisher’s affidavit).

6) Completing and proving service

After the court grants your motion and you execute the authorized steps:

File an Affidavit of Service (by the sheriff or authorized server) detailing dates, times, and manner of service.
Attach documentary proof: publication affidavits and tear sheets, registry receipts and tracking, courier certifications, email server logs/“delivered” headers, screenshots of social-media delivery/read receipts, and any replies.

The period to answer runs from the last step the court specified (e.g., completion of publication), not from your filing date.

7) If service fails or is later attacked

Invalid service deprives the court of jurisdiction over the person; any judgment may be void as to the father.
If the respondent voluntarily appears (files an answer or seeks affirmative relief without objecting to service), the defect is cured and the court acquires jurisdiction.
If the court denies your motion for publication/electronic service, you must augment your diligent search and try again with stronger proof or a different mode.

8) Provisional support without personal service?

Courts are cautious. Some judges may issue limited provisional orders (e.g., interim support sourced from assets or known pay channels) after constructive service (publication/e-service) and non-appearance, but most prefer to ensure strict compliance with service requirements first. Best practice is to move for support pendente lite as soon as service is deemed complete under the court’s order.

9) Practical evidentiary strategies when the address is unknown

Means and capacity: If you cannot locate him but know his occupation/employer, gather public or secondary indicators of income: professional license listings, business permits, company directories, public social-media displays of work, lifestyle evidence.
Needs of the child: File a budget matrix (tuition, food, rent share, utilities, transport, medical, incidentals) with receipts/quotations.
Arrears computation: Provide a month-by-month table of unpaid support and any partial remittances.

10) Interaction with barangay conciliation and criminal remedies

Katarungang Pambarangay conciliation is generally not a prerequisite for support cases when parties reside in different cities/municipalities or when the matter involves the status of persons.
For economic abuse in intimate-partner contexts, RA 9262 (VAWC) provides criminal and protection-order remedies; service of criminal processes follows different rules and should not be conflated with civil summons for support.

11) Checklist: documents to prepare

Petition for support + verification and certification of non-forum shopping
Affidavit of Diligent Search and Inquiry with exhibits
Motion for leave to serve by special means (e-service/publication/substituted/extraterritorial) + proposed order
Motion for support pendente lite with child-needs matrix and proofs
Proofs of filiation (birth certificate, acknowledgment, communications, remittances)
Proof of attempts to locate/respondent’s last known identifiers (emails, handles, phone numbers)
After service: Affidavit of Service and publisher/courier/email proofs

12) Frequent pitfalls (and how to avoid them)

Generic affidavits (“we searched but he’s gone”) → Provide dates, places, names, numbers, and documentary proof.
Skipping leave of court before e-service/publication → Always secure prior judicial authorization.
Relying on one mode only → Seek combined modes (publication + registered mail + email + social-media DM) to strengthen due-process compliance.
Incorrect venue → File where the child/petitioner resides to avoid dismissal.
No follow-through on proof of service → File comprehensive proofs; the clock for the father’s answer hinges on completion.

13) Model snippets (for guidance only)

Affidavit of Diligent Search — key paragraphs

“Since 15 January 2025, I have exerted the following efforts to ascertain respondent’s present address: (a) visited his last known residence at 123 Mabini St., Barangay Malinis, Quezon City on 20 January, 27 January, and 10 February 2025 and spoke with Mr. Santos (caretaker), who stated respondent moved out in March 2024; (b) inquired with Barangay Malinis and obtained the attached Certification dated 12 February 2025; (c) emailed respondent at juan.delacruz@example.com on 05 and 19 February 2025 (Annexes __) with no reply; (d) sent registered letters on 06 February 2025 to his last known address which were returned ‘Moved Out’ (Annexes __); (e) messaged his verified Facebook account @JuanDC on 07 and 21 February 2025 (screenshots Annexes __); (f) called his known mobile 09xx-xxx-xxxx on 5 occasions (call logs Annex __); and (g) asked his sister, Maria Dela Cruz, who stated she has not known his address since August 2024 (Annex __).”

Prayer for special service (publication + electronic)

“Petitioner respectfully prays for leave of court to serve summons (i) by publication once a week for three consecutive weeks in a newspaper of general circulation, (ii) by sending scanned summons and petition to respondent’s known email juan.delacruz@example.com, (iii) by private message to his verified Facebook handle @JuanDC, and (iv) by registered mail to his last known address, with service deemed complete upon completion of publication, without prejudice to earlier actual receipt.”

14) Bottom line

You can move a child-support case forward even if the father’s address is unknown, but you must (1) document a genuine, detailed hunt for him, and (2) obtain the court’s leave for substituted, electronic, publication, or extraterritorial service that is reasonably calculated to give notice. Strong diligence plus layered service methods will protect your case from jurisdictional attack and speed up interim relief for the child.