A method for allocating destination calls in an elevator system, the system including at least one multi-deck elevator, where the passenger gives his/her destination floor by means of a destination call device at the beginning of the journey route, thereby defining the staffing point and final point of the passenger's journey route in the elevator system. The method includes the steps of generating possible route alternatives from the staffing point to the final point of the journey route, determining a cost function containing at least one travel time term, determining the value of the travel time term corresponding to each route alternative in the cost function, calculating the total cost of each route alternative by using the cost function, allocating for the passenger the route alternative that gives the minimum total cost, and guiding the passenger to a waiting lobby and/or elevator consistent with the route alternative allocated.