In our work we study the problem of Longevity Risk management and particular interest is given to “revaluating” life annuities. We propose a life annuity model where the payout payment changes dynamically in relation to the fluctuations in the investment return and to the actual mortality trends. The model proposed is effective because, at every annual expiry, the Insurance Company is able to guarantee the life benefit liabilities to an insured collectivity, homogeneous in age and contract model; moreover, it is efficient because, at every annual expiry, also in the presence of unforeseen variations of mortality rates, the Insurance Company has exactly got the mathematical reserve useful to pay annuities to the collectivity members who are still living.