Compulsory expenditures
Also called "obligatory expenditures", this is an expenditure with its origin in the treaties or in already adopted legislation.
This part of the EU budget deals mainly with agriculture, over which the Council has the "final say".
The Lisbon Treaty has abolished the difference between compulsory and non-compulsory expenditures, thereby increasing the powers of the European Parliament.
Links
EU Budget at a glance http://ec.europa.eu/budget/budget_glance/index_en.htm
See also non-compulsory expenditures.