In this paper we propose a multi-state model for the evaluation of the conversion option contract. The multi-state model is based on age-indexed semi-Markov chains that are able to reproduce many important aspects that influence the valuation of the option such as the duration problem, the time non-homogeneity and the ageing effect. The value of the conversion option is evaluated after the formal description of this contract.Keywords Semi-Markov chain, temporary insurance policy, permanent insurance policy 2010 MSC 60K15, 90B25 ✩ This work is dedicated to Prof. Dmitrii Silvestrov in recognition of his contribution to actuarial mathematics.