In the JET tokamak, the presence of the iron core distorts the configuration of the magnetic fields that holds the plasma in equilibrium, changes the shape of the plasma boundary, and substantially affects the plasma configuration. Therefore, a correct iron core model can improve the accuracy of an equilibrium code. We report here a description of the finite element CREATE-I reconstruction code, in which the iron transformer is implemented in a different way with respect to the code routinely used at JET (EFITJ [1]), both in terms of geometry and treatment of the equations. Results of comparative calculations using magnetic and MSE experimental data are presented.