This paper calculates the degree of intragenerational income mobility and carries out the decomposition of the influence of observable characteristics on income mobility. Using the concept of mobility as the equalization of longer-term incomes, we quantify the class of measures called the E index using administrative records for social security contributions of formally employed young adults in Colombia between 2010 and 2018. In addition, we use the Recentered Influence Function (RIF) decomposition method to extend its application to the E index and decompose the influence of observable characteristics on our estimates. Our findings indicate Colombia's mobility is disequalizing. We also show that female mobility is even more disequalizing than male mobility. Our decomposition shows that disequalizing mobility depends on employees' type of contract, economic sector, and location.