Additionality

[Jessica]

the situation in which a government or organization is able to get money for a project from another government or organization, especially the European Union, only if it pays for most of the project itself:

[Britney]

The fact or concept of being additional; especially any principle or policy that involves pursuing economic or financial practice according to this concept; specifically (in the European Union) the requirement that central funding should supplement, and not replace, national expenditure on a project.