Article 28 Revised Penal Code
Article 28 of the Revised Penal Code is about Computation of penalties. It is under Chapter Three (Duration And Effects Of Penalties) of Title Three (Penalties) of the Code.
Computation of penalties
If the offender shall be in prison, the term of the duration of the temporary penalties shall be computed from the day on which the judgment of conviction shall have become final.
If the offender be not in prison, the term of the duration of the penalty consisting of deprivation of liberty shall be computed from the day that the offender is placed at the disposal of the judicial authorities for the enforcement of the penalty. The duration of the other penalties shall be computed only from the day on which the defendant commences to serve his sentence.
See also: Article 27 Revised Penal Code