The task of comparing social policies has focused primarily on quantifying the outputs, but leaves out an important factor for policy to be carried out, as is the quantification of the inputs. This paper focuses in the government effort to financing and implementing social policies. The goal is to present the results of the implementation of Social Policy Index+ (SPI+) in the United Kingdom and Chile from 2005 to 2012, establishing a transatlantic comparison of the inputs of social policy in two countries with a liberal welfare model. The research question is: Does SPI+ allows us to establish differentiation between countries that belong to the same welfare regime at different continents? To achieve this, the study uses the SPI+ as a tool for measuring and comparing transatlantic social policies. Through a comparative analysis of SPI+ results with a contextual description it is possible to confirm the consistency of the instrument for defining subgroups within specific welfare models, that also allows measure, classify and properly compare the two countries studied.