In the Philippine criminal justice system, the determination of a penalty does not end with a finding of guilt. When an accused is convicted of several offenses—whether in a single case or across multiple separate trials—the manner in which those sentences are served becomes a critical legal question. Philippine law, primarily through the Revised Penal Code (RPC), provides a specific hierarchy and set of rules to govern the service of multiple penalties.

1. The General Rule: Successive Service

The foundational principle under Article 70 of the Revised Penal Code is that when a culprit has to serve two or more penalties, they shall be served simultaneously if the nature of the penalties permits. However, if they cannot be served simultaneously (which is the case for most custodial sentences like reclusion perpetua or prision mayor), they must be served successively.

The order of payment or service follows the severity of the punishment, starting with the most severe penalty. The legal hierarchy generally follows this order:

Death (though currently prohibited and replaced by reclusion perpetua)
Reclusion Perpetua
Reclusion Temporal
Prision Mayor
Prision Correccional
Arresto Mayor
Arresto Menor

2. The Three-Fold Rule: The Ceiling of Punishment

The most significant protection for a convict facing a long list of successive sentences is the Three-Fold Rule.

Under Article 70, the maximum duration of the convict's sentence shall not exceed three times the most severe penalty imposed upon them. Furthermore, regardless of the mathematical result of that tripling, the total period of imprisonment can never exceed forty (40) years.

How the Calculation Works

Scenario A: A person is convicted of five counts of a crime, each carrying a 6-year sentence. The "most severe" is 6 years. Three times 6 is 18. Instead of serving 30 years (5 x 6), the convict will only serve 18 years.
Scenario B: A person is convicted of multiple crimes where the most severe penalty is 20 years. Three times 20 is 60. However, because of the absolute legal ceiling, the convict will only serve 40 years.

3. Complex Crimes vs. Separate Crimes

The manner of sentencing often depends on how the crimes were committed.

Complex Crimes (Article 48): When a single act constitutes two or more grave or less grave felonies, or when an offense is a necessary means for committing the other, the law imposes the penalty for the most serious crime in its maximum period. In this case, there is only one sentence to serve.
Separate Crimes: If the crimes are distinct acts (e.g., three separate robberies on three different nights), they result in multiple counts, triggering the successive service and the Three-Fold Rule.

4. Subsidiary Imprisonment

When a convict is ordered to pay a fine or civil liability but is insolvent (unable to pay), the law imposes subsidiary imprisonment—extra time in jail to "pay off" the debt.

However, there are strict limitations:

Subsidiary imprisonment cannot be imposed if the principal penalty is higher than prision correccional (6 years).
It cannot exceed one-third of the principal penalty.
In no case can it exceed one year.
If the Three-Fold Rule is applied and the convict has already reached the 40-year limit, subsidiary imprisonment can no longer be imposed.

5. Credit for Preventive Imprisonment

Under Republic Act No. 10592, a convict is entitled to have the time they spent in jail while awaiting trial (preventive imprisonment) deducted from their total sentence.

Full Credit: If the prisoner agreed in writing to abide by the same disciplinary rules as convicted prisoners during their detention.
Four-Fifths Credit: If they did not agree to such rules.

6. Good Conduct Time Allowance (GCTA)

The actual time served may be further reduced by Good Conduct Time Allowance (GCTA). This is a statutory mechanism that rewards "good behavior" with days off the sentence.

RA 10592 expanded these allowances significantly.
However, it is important to note that recidivists, habitual delinquents, escapees, and those convicted of "Heinous Crimes" are excluded from the benefits of GCTA under current implementing rules and jurisprudence.

7. Habitual Delinquency

While the Three-Fold Rule favors the convict, the law on Habitual Delinquency (Article 62) increases the penalty. A person is a habitual delinquent if, within ten years from their last conviction or release, they are found guilty a third time or more for specific crimes (Robbery, Theft, Estafa, Falsification, or Physical Injuries). They receive an additional penalty on top of the principal penalty for their latest crime, which must also be served successively.