With the implementation of Act 100 of 1993, it began to reform Social Security System in Health in Colombia, seeking efficiency and universal coverage, this system currently has two schemes, the contributory scheme and the subsidized regime, which order to subsidize the provision of health services for people without ability to pay. This paper focuses its interest in the theoretical basis for assessing the financial sustainability of Subsidized health regime, with a detailed description of funding sources that shape, behavior and evolution. Then it proposes a method for projecting revenues by source of funding and determining the amount of estimated resources with which the State would have to guarantee access to health services for the poor, potential beneficiaries of the subsidized health regime.