The correct simulation of metal flow and temperature profiles during filling is an essential part of an overall numerical simulation that includes solidification. An algorithm for modeling the filling of metal into a mold and solidification heat transfer is developed. This algorithm uses the implicit VOF method for filling and a general implicit source-based method for solidification. Implicit solutions based on this modified scheme are smear free at moderate large time steps. The model for simultaneous filling and solidification is applied to the simple two-dimensional filling and solidification of a square cavity. It is shown that a coupled analysis of filling and solidification processes must be considered to obtain more realistic results in the casting process. The modified implicit algorithm is also presented to handle a sloshing problem.