Situation: An illegitimate child dies with no children, whether legitimate or illegitimate, and without a last will.
 If that illegitimate child was unmarried, then the biological father or mother will inherit. If both parents are still alive, they will inherit on a 50-50 basis under Article 993 of the New Civil Code of the Philippines.
Art. 993. If an illegitimate child should die without issue, either legitimate or illegitimate, his father or mother shall succeed to his entire estate; and if the child's filiation is duly proved as to both parents, who are both living, they shall inherit from him share and share alike.Question: What if you are an illegitimate child raised by your mother alone, with your biological father providing nothing at all? Can you prevent your father from inheriting from you?
Answer: If you die without a last will, then your deadbeat father will inherit from you under Article 993. You must therefore execute a last will disinheriting your father based on Article 920 of the New Civil Code of the Philippines. The requirements for a valid disinheritance under Article 918 are very strict (see the chart below); you must consult a very competent notary public.
 If the illegitimate child was married and the parents are also dead, then the spouse will inherit everything under Article 994 of the New Civil Code of the Philippines.
Art. 994. In default of the father or mother, an illegitimate child shall be succeeded by his or her surviving spouse who shall be entitled to the entire estate.But as stated in the 2nd paragraph of Art. 994, if the deceased illegitimate child has illegitimate siblings, then the spouse will share the inheritance with them on a 50-50 basis. (The siblings will divide among themselves the 50% allotted to them.) If any of the illegitimate siblings had died beforehand, then the sons and daughters (the nephews and nieces of the illegitimate child) will inherit their deceased parent’s share.
If the widow or widower should survive with brothers and sisters, nephews and nieces, she or he shall inherit one-half of the estate, and the latter the other half.
Question: What if the illegitimate child was unmarried but has illegitimate siblings?
Answer: Although Article 994 does not state it, the illegitimate siblings (together with the nephews and nieces of any sibling who died beforehand) will inherit everything.
Requirements and grounds for a valid disinheritance (click the picture to see the clearer, enlarged view)