Short answer. A light felony is an infraction punished by arresto menor, a fine not exceeding forty thousand pesos, or both. Article 9 sets that ceiling, and the forty-thousand-peso figure is the amount as revised by RA 10951 in 2017 — not the original, much smaller 1930 figure some sources still show.
What the law says
Light felonies are those infractions of law or the commission of which the penalty of arresto menor or a fine not exceeding Forty thousand pesos (₱40,000) or both is provided.
Revised Penal Code, Article 9 — Grave, Less Grave, Light Felonies. Read the full provision →
Light felony: the lightest of the three categories
Article 9 defines light felonies as those infractions of law or the commission of which the penalty of arresto menor or a fine not exceeding Forty thousand pesos (₱40,000) or both is provided. This sits at the bottom of the three-tier system the article sets up, below grave felonies, which carry capital punishment or afflictive penalties, and less grave felonies, which carry correctional penalties in their maximum period, according to the same scale of penalties.
Arresto menor, a fine, or both
The article gives three possible ways a light felony can be punished: through arresto menor alone, through a fine not exceeding Forty thousand pesos alone, or through both together. Which of these actually applies to a specific offense depends on how the particular provision defining that offense is written, since Article 9 only sets the outer boundary of what qualifies as light rather than fixing one single punishment for every light felony that falls within it.
The forty-thousand-peso ceiling reflects RA 10951's 2017 revision
The forty thousand peso figure is not the amount originally written into the 1930 Revised Penal Code. Republic Act No. 10951, enacted in 2017, revised the fines and property values used throughout the Code, including this ceiling. Older reproductions of the Code still in circulation may show a much smaller original figure, so anyone relying on this threshold should confirm it reflects the amount as revised by RA 10951, rather than the outdated figure some older references still carry.
Why the classification matters beyond the label
Whether an offense counts as a light felony affects more than just how severe the punishment sounds — the classification carries consequences elsewhere in the Code, such as how prescription periods and certain procedural rules apply differently depending on whether a felony is grave, less grave, or light. Confirming that a specific offense's penalty actually falls within Article 9's light-felony threshold is therefore a necessary first step before working out how those other rules apply to it, rather than assuming the classification from the offense's label alone.