Short answer. Anger alone is not the crime. Inciting to sedition punishes a person who, without joining sedition himself, urges others toward seditious acts through speeches, writings, cartoons, banners or similar means, or who utters seditious words or circulates scurrilous libels against the Government. The current penalty and fine come from Republic Act No. 10951 (2017).
What the law says
should incite others to the accomplishment of any of the acts which constitute sedition by means of speeches, proclamations, writings, emblems, cartoons, banners, or other representations tending to the same end
Revised Penal Code, Article 142 — Inciting To Sedition. Read the full provision →
The reader's real question: is my post a crime?
Most people who search this are not organising anything. They posted something furious about an official or a police operation and someone told them it was sedition. The article is aimed at a narrower target than that. What it punishes is inciting — urging other people toward the acts that make up the separate crime of sedition, which is a public and tumultuous rising to attain certain unlawful ends by force or intimidation. A post that insults, criticises or condemns is not, without more, an incitement to that. The Constitution protects a great deal of harsh political speech, and criticism of government is squarely within it.
What the article actually covers
The provision reaches a person who takes no direct part in sedition but pushes others toward it through speeches, proclamations, writings, emblems, cartoons, banners, or other representations tending to the same end. It goes on to cover uttering seditious words or speeches and writing, publishing or circulating scurrilous libels against the Government or its duly constituted authorities, along with words tending to obstruct a lawful officer, to instigate others to cabal and meet for unlawful purposes, to incite rebellious conspiracies or riots, or to stir the people up against lawful authorities. It also reaches one who knowingly conceals such practices. The medium does not matter; the tendency of the words does.
The penalty today
The penalty is prisión correccional in its maximum period and a fine. The peso figure now in force — not exceeding four hundred thousand pesos — comes from Republic Act No. 10951, enacted in 2017, which revised fines and property values throughout the Revised Penal Code. This matters when you research online. Many reproductions of the Code still print the 1930 amounts, so an article or a forum answer quoting a much smaller fine is simply out of date. Always check which version of the Code a source is giving you before relying on any peso figure in a criminal provision.
If a complaint has been filed against you
Do not argue the merits on social media, and do not delete and re-post, which can look worse than the original. Preserve the exact wording, the date, the context and the thread it sat in, because context is often what separates protected criticism from an incitement. A complaint of this kind usually begins with a preliminary investigation before a prosecutor, where you are given the chance to answer in writing — that answer is the most important document in the case, and it should be prepared with counsel. No lawyer can promise how a prosecutor or court will rule, but the difference between an early, well-prepared answer and a late improvised one is real.