The adjusted population is the main mechanism used to calculate the funds each autonomous community should receive. It is based on the total population census, but corrected according to a series of weighted criteria, with the theoretical goal of ensuring that all citizens have equivalent social benefits, regardless of where they live in Spain.

However, economics professors like Joaquim Solé of the University of Barcelona warn that this mechanism, despite offering a veneer of scientific rigor, is easily manipulated. Furthermore, neither the current 2009 model nor the proposed one includes a crucial variable: the cost of living in each community, which significantly affects the final outcome of social benefits.

Minister Montero's proposal slightly modifies the 2009 model. The main weights remain: real population accounts for 30%, health expenditure for 38%, and education investment for 20.5%. The main novelty is the diversification of age groups in healthcare (from 7 to 20 brackets) and the segregation of higher education.

This equalization system means that 75% of the taxes collected by the communities go into a common fund distributed according to the adjusted population. Currently, only three autonomies are net contributors, providing more than they receive: Madrid, the Balearic Islands, and Catalonia. Professor Núria Bosch points out that although it is assured that Catalonia will be the third in receiving funds per capita, the concept of ordinality has not been put in writing.