The (Callaghan) Retirement Income Review suggested that superannuation tax concessions are excessive, especially for those on higher incomes, and questioned their use other than to fund the superannuant’s living expenses. Favourable fiscal arrangements for superannuation are pervasive across the OECD. A common justification is that applying the tax treatment of ordinary investments would result in unreasonably harsh and inequitable burdens. This is illustrated in a scenario in which additional income is earned for the purpose of boosting the person’s superannuation account. As indicators of favourable treatment, the Review reported estimates of marginal effective tax rates, calculated for investment scenarios. I show how these rates vary greatly with reasonable variations in the formulation of the index being used. Moreover, an intuitive index of the rate of tax concession is to be preferred; on the OECD estimates, Australia’s rate is around the median, at 24 percent. I justify an economic formulation of effective tax rates which better expresses the impact of taxes on behaviour and on welfare than the conventional legalistic formulation. Especially in relation to retired middle-income earners, the claim that the taxation of superannuation is unduly concessional turns out to be at best unproven, and so, as a result, that claim cannot properly be used to support further public policy interventions affecting the use of savings in retirement, nor for not increasing the rate of the Superannuation Guarantee Levy.