To claim or demand support, the single mother must prove first that the child is related to the putative father.
When a man refuses to recognize a child as his, there is no other recourse but to file a petition compulsory recognition of an illegitimate child in the courts and only when filiation is proved, only then the courts can force a man to recognize his child. The Petition must be filed during the lifetime of the alleged parent.
If the parent and son relationship is in issue, the relationship should be established first before support can be demanded. The civil status of sonship being denied and this civil status, from which the right to support is derived, being in issue, it is apparent that no effect can be given to such a claim until an authoritative declaration has been made as to the existence of the cause. (Francisco vs. Zandueta, 61 Phil. 752)
There must be a declaration of the status of the child from which the right to support is derived and before support can be ordered. Such a declaration may be provisional, that is, by affidavits. (Mangulabnan vs. IAC, 185 SCRA 760)
When there is no proof of filiation, the man does not have to recognize the child and furthermore, support may not be granted since there is no basis that the man is the father.
Only when the filiation issue is resolved that the single mother can rightfully demand for child support, and this is best done in writing, with proof that such demand was received by the father. If the father of the child refuses to provide child support despite receiving a written demand, the single mother can now sue the father for child support.
Republic Act No. 9262, otherwise known as the “Anti-Violence Against Women and their Children Act of 2004“ provides for criminal sactions or penalties for failure to provide support or withholding support, in certain cases.