And, furthermore, the question of jurisdiction attempted to be raised in this case is not the kind of question that confers jurisdiction upon this Court. The jurisdiction involved is not one over the subject matter but at most over the issue or over the persons of the parties. A Court of First Instance has jurisdiction over the case involving P200 or more, and therefore the Court of First Instance of Nueva Ecija had jurisdiction to render judgment in the amount of P350. The question of whether or not there was a proper issue raised in the pleading as to said amount, is not a question of jurisdiction over the subject-matter, but jurisdiction over the issue. In this regard we reiterate what we have said in Reyes vs. Diaz, G.R. No. 48754, November 26, 1941: There is in our Constitution or in the law aforecited nothing which may lend the word "jurisdiction" therein used a broader meaning than jurisdiction over the subject-matter. On the contrary, having due regard to the manifest purpose of the law, which is to confine the appellate jurisdiction of this Court to cases of vital importance involving questions of fundamental character, such, for instance, as the question validity of statute, treaty or ordinance, or the legality of any tax, import or assessment which may affect the very existence of the government, or criminal cases wherein life imprisonment or death penalty is imposed, we are of the opinion and so hold., that the issue of jurisdiction which confers appellate powers upon this Court in a given case is not such question as is dependent exclusively upon minor matters of fact or upon a mere construction of the pleadings, but that which has reference to the more important question of jurisdiction of the trial court over the subject-matter as determined by law.

Jurisdiction over the subject-matter is the power to hear and determine cases of the general class to which the proceedings in question belong (C. J. S. p. 36) and is conferred by the sovereign authority which organizes the court and defines the court and defines its powers (Banco Espa�ol Filipino vs. Palanca, 37 Phil., 921; Perkins vs. Dizon, 40 Off Gaz., No. 7, 3rd Sup., p., 216; Ng Si Chok vs. Vera, G. R. No. 45674). The question, therefore of whether a court has jurisdiction over the subject-matter, calls for interpretation and application of the law of jurisdiction which distributes the judicial power among the different courts in the Philippines and since the ruling on the matter is of far-reaching consequences, affecting, as it may, the very life and structure of our judicial system, the law has deemed it wise to place the power and authority to act thereon in the highest court of the land. xxx xxx xxx

... Whether certain ballots are or are not pertinent to the issue raised in the pleadings, is merely a question of relevancy of evidence. It may be true that the court by an erroneous ruling on such question may encroach upon issues completely foreign to those defined in the pleadings, but in such case the question of jurisdiction that may arise would not be one of jurisdiction over the subject-matter but of jurisdiction over the issue. In order that a court may validly try and decide a case, it must have jurisdiction over the subject-matter and jurisdiction over the persons of the parties (Banco Espa�ol Filipino vs. Palanca, 37 Phil., 921; Perkins vs. Dizon, 40 Off. Gaz., No. 7, 3d Sup., p., 216.) But in some instances it is said that the court should also have jurisdiction over the issue (15 C. J., 734; Hutts vs. Martin, 134 Ind., 587; 33 N. E., 676), meaning thereby that the issue being tried and decided by the court be within the issues raised in the pleadings. But this kind of jurisdiction should be distinguished from jurisdiction over the subject matter, the latter being conferred by law and the former by the pleadings.

Jurisdiction over the issue, unlike jurisdiction over the subject-matter, may be conferred by consent either express or implied of the parties. (Rule 17, sec. 4, Rules of Court.) Although an issue is not duly pleaded it may validly be tried and decided if no timely objection is made thereto by the parties. This cannot be done when jurisdiction over the subject-matter is involved. In truth, jurisdiction over the issue is an expression of a principle that is involved in jurisdiction over the persons of the parties. Where, for instance, an issue is not duly pleaded in the complaint, the defendant cannot be said to have been served with process as to that issue. (Cf. Atkins, Kroll & Co. vs. Domingo, 44 Phil., 680.) At any rate, whether or not the court has jurisdiction over a specific issue is a question that requires nothing except an examination of the pleadings, and this function is without such importance as to call for the intervention of this court. G.R. No. L-48652, September 16, 1942

Jurisdiction over the subject-matter is the power to hear and determine cases of the general class to which the proceedings in question belong (C. J. S., p. 36) and is conferred by the sovereign authority which organizes the court and defines its powers (Banco Espa�ol Filipino vs. Palanca, 37 Phil. 921; Perkins vs. Dizon, 40 Off. Gaz. No. 7, 3d Sup. p. 216; Ng Si Chok vs. Vera, G.R. No. 45674). The question, therefore, of whether a court has jurisdiction over the subject-matter, calls for interpretation and application of the law of jurisdiction which distributes the judicial power among the different courts in the Philippines, and since the ruling on the matter is of far-reaching consequences, affecting, as it may, the very life and structure of our judicial system, the law has deemed it wise to place the power and authority to act thereon in the highest court of the land.

In the instant, case, there is no such question of jurisdiction as above described. Both parties agree that if the due filing of the protestant's certificate of candidacy is proven, the trial court has no jurisdiction except to dismiss the case. There is, therefore, no question between the parties as to what the jurisdiction of the trial court is according to law in either case. The real question between them is one of fact � whether or not the protestant's certificate of candidacy has been duly filed. And not the until this fact is proved can the question of jurisdiction be determined. G.R. No. L-48754, November 26, 1941.

The General rule is lack of jurisdiction over the subject matter may be raised any time, at any stage of the proceedings.

Exception: Where a party actively participates in all stages of the proceedings without objecting to the court's jurisdiction, he can no longer raise the issue of jurisdiction after obtaining an unfavorable Decision. http://www.lawphil.net/judjuris/juri1968/apr1968/gr_l-21450_1968.html

Ceroferr Realty vs. CA - "While the lack of jurisdiction of a court may be raised at any stage of an action, nevertheless, the party raising such question may be estopped if he has actively taken part in the very proceedings which he questions and he only objects to the court�s jurisdiction because the judgment or the order subsequently rendered is adverse to him." http://www.supremecourt.gov.ph/jurisprudence/2002/feb2002/139539.htm