Under Philippine law, providing support to a child is not merely a moral obligation but a mandatory legal duty. The Family Code of the Philippines explicitly states that parents are obliged to support their children, regardless of whether the child is legitimate or illegitimate. When a father fails to fulfill this responsibility, the custodial parent or guardian has several legal avenues to compel compliance.

1. Legal Basis for Support

The primary law governing child support is Executive Order No. 209, otherwise known as the Family Code of the Philippines.

Article 194: Defines support as everything indispensable for sustenance, dwelling, clothing, medical attendance, education, and transportation, in keeping with the financial capacity of the family.
Article 195: Mandates that parents and their children (legitimate or illegitimate) are contractually and legally obliged to support each other.

2. Preliminary Step: The Barangay Conciliation

Before filing a formal case in court, Philippine law generally requires the parties to undergo Barangay Conciliation (mediation) under the Katarungang Pambarangay system.

File a Complaint: Visit the Lupong Tagapamayapa of the barangay where the respondent (father) resides.
Mediation: A hearing will be scheduled to reach an amicable settlement.
Kasunduan: If an agreement is reached, it is reduced to writing. This "Kasunduan" has the force and effect of a court judgment after 15 days, provided it is not repudiated.
Certificate to File Action: If mediation fails, the Barangay Captain will issue a certificate allowing the complainant to elevate the matter to court.

3. Options for Legal Action

A. Civil Case for Support

This is a petition filed in the Regional Trial Court (Family Court) to demand a monthly allowance.

Support Pendente Lite: You can petition the court for "support during the pendency of the case." This allows the child to receive financial assistance immediately while the main case is still being litigated.
The "Amount of Support" Rule: There is no fixed "minimum" amount in the Philippines. The court determines the amount based on the "Proportionate Principle": the necessities of the child versus the financial capacity/means of the father.

B. Criminal Case under R.A. 9262

The Anti-Violence Against Women and Their Children Act of 2004 (R.A. 9262) classifies the "willful" denial of financial support as a form of Economic Abuse.

Penalty: This is a criminal offense that can lead to imprisonment.
Protection Orders: A victim can apply for a Barangay Protection Order (BPO) or a Temporary/Permanent Protection Order (TPO/PPO) from the court, which can include a provision for immediate support and a "Withholding of Salary" order directed at the father’s employer.

4. Documentary Requirements

To build a strong case, the following documents are typically required:

PSA Birth Certificate of the Child: To prove the filiation (relationship) between the father and the child. If the father's name is not on the birth certificate, a separate action for "Recognition" or "Compulsory Recognition" may be needed first.
Marriage Contract: If applicable.
List of Expenses: A breakdown of the child’s monthly needs (school tuition, food, milk, medical records, etc.).
Evidence of Father’s Income: Pay slips, business permits, or social media posts showing lifestyle/capacity to pay.
Certificate to File Action: From the Barangay.

5. Filing Process for Indigents

If the custodial parent cannot afford legal counsel, they may seek assistance from:

Public Attorney’s Office (PAO): They provide free legal representation to "indigent" litigants (those whose income falls below a specific threshold).
Integrated Bar of the Philippines (IBP): Most chapters have legal aid committees for marginalized clients.
Department of Social Welfare and Development (DSWD): While they cannot litigate, they can provide social worker interventions and assistance in mediation.

6. Enforcement of Support

Once a court issues a Decision or a Support Order:

Garnishment: If the father is employed, the court can order his employer to automatically deduct the support amount from his salary and remit it directly to the mother/guardian.
Contempt of Court: If the father refuses to pay despite a court order, he can be cited for indirect contempt, which may result in fines or imprisonment until he complies.
Hold Departure Order (HDO): In some R.A. 9262 cases, the court may issue an HDO to prevent the father from leaving the country to evade his obligations.

Key Reminders

Illegitimate Children: Under the law, illegitimate children are entitled to support just like legitimate ones. The only hurdle is proving paternity (through the birth certificate signed by the father or other "authentic writing").
Support Never Prescribes: The right to claim future support cannot be waived or renounced. Even if the mother previously agreed not to ask for money, she can still file a case later because the right belongs to the child.