The transmission usage cost allocation is one of the major issues experienced by the Electric Supply Industries. In this paper, authors have considered Line Outage Distribution Factor (LODF) for allocating the transmission usage cost allocation under contingency condition. Authors have modified the distribution factor for maximum flow and propose a novel Maximum Line Outage Distribution Factor (MLODF) which depends upon the redistribution of the generation in the line flow considering N-1 security constraints. Similarly, for transmission loss cost allocation under contingency condition Maximum Line Outage Loss Distribution Factor (MLOLDF) is developed. Full recovery policy of transmission cost allocation is considered. The reliability and accuracy of the proposed method is tested on the sample 6 bus system.