As implemented in Administrative Order (AO) No. 1, Series of 1993, the Implementing Rules and Regulations of Act No. 3753, the following general rules shall apply in the registration of birth of an illegitimate child born before August 3, 1988:

• Born AFTER August 3, 1988
  • Birth Certificate already registered and child is under the surname of the Mother and a Private Handwritten Instrument (PHI) by the father is present.
  • Birth Certificate already registered and child is under the surname of the Mother and Father executed an affidavit of acknowledgement.
  • Birth Certificate is not yet registered and the father acknowledges the child at the back of the birth certificate or in a separate public instrument.