Abstract The real time EPIC-PHASE model developed at Toulouse Auzeville INRA was tested on a maize crop. The main objective of the trial was to evaluate the potential of the model in real time tactical irrigation management based on model predictions every 5 days. The trial compared the results of management using simple decision-making rules (SDR) with those resulting from model management (MOD). Compared with the standard version of EPIC, which is capable of simulating the evolution of soil water content, the option of real time enables integration of intermediate states and realization of step-by-step simulations. The trial reported here has demonstrated that it is possible to simulate different irrigation tactics and, hence, different irrigation amounts with weather forecasts. Results from the study showed that discrepancies between actual and weather forecasts led to a difference in tactical irrigation management. Retrospective simulation carried out with observed data demonstrated the capabilities of the model under non-limited water supply, to be used as an irrigation management tool to save water and reach a similar level of yield. Use of the model also reduced the risk of overirrigation and associated nitrogen leaching.