For questions related to the Catholic/Orthodox concepts of merit, treasury of merit, supererogation, and superabundant merit of Christ. Also for Protestant objections of how those 4 concepts are used by Catholics.

For the definitions of the 4 concepts treated under this tag, see the following articles:

The reason for using a single tag for all 4 concepts is the tight linking among them under the umbrella of communion-of-saints. See this article.

Please note that these concepts are a lot more ancient (pre-St. Augustine) than the 16th century indulgence controversy, which should be understood as the Roman Catholic scheme for the distribution of merit, which Eastern Orthodox disagrees. This article by an Orthodox theologian makes a good case for the catholicity of merit before any schisms, as well as how the teaching on merit is independent of the Roman Catholic church's claim of holding the keys over indulgence.