Calculation of tax sought to be evaded clarified, affecting penalty computation and applicable adjustments for prior tax payments and losses. Amendment prescribes a formulaic determination of the amount of tax sought to be evaded by summing two components: the tax difference under general provisions and the tax difference under alternative tax provisions, each measured as tax on total assessed income minus tax that would have been chargeable had the concealed or misstated income been excluded; the alternative component is ignored if inapplicable and double reduction for the same income is prohibited. Where concealed income reduces or converts a loss, the general component is replaced by tax that would have been chargeable had the concealed income been the total income, and amounts of tax paid before reassessment notice are to be deducted where applicable.