INCOMPATIBILITY OF BENEFICES. — According to can. 1439, incompatible benefices cannot be accepted and retained either in title or in perpetual commendam, that is, those whose obligations cannot be fulfilled together by the same beneficiary or of which one would suffice for the beneficiary’s livelihood. The source of the incompatibility of benefices is therefore twofold: 1) the impossibility in which the holder of two or more residential or curate benefices, whether major or minor, finds himself of performing all his duties simultaneously, as in the case of two bishoprics, two canonries, two parishes, etc.; 2) the fact that one of the benefices is sufficient for the honest support of the beneficiary. The judgment on this second point is left to the prudent discretion of the Ordinary. Any incompatibility of benefices ceases if the benefices, which are by nature incompatible, are canonically united in perpetuity, in accordance with can. 339 § 5, 460 § 1, 1949.
The plurality or accumulation of benefices was prohibited as early as the 5th-century Councils, with various penalties that became increasingly severe under the pontificates of Alexander III, Innocent III, Boniface VIII, Clement V, and John XXII. Here too, the Council of Trent abolished all exceptions that especially the nobility and learned persons had managed to obtain.
In current law, the acceptance of incompatible benefices renders the provision invalid; indeed, upon acceptance of the second benefice, the first one lapses (can. 188, 3).
Moreover, whoever, having obtained an office or benefice incompatible with a previous one, presumes to retain both, is deprived of both (can. 2396).
From this law of common law, only the Supreme Pontiff can grant a dispensation, and the dispensation will be valid only if the petitioner, in his request, has mentioned the previous incompatible office or benefice, or if the concession contains a clause derogating from the common law (can. 156 § 3).