The results of the operation of the various state income taxes, judged in the light of the relative tax-paying capacity of the incomes of residents, indicate financial success on the one hand and financial inadequacy and failure on the other. Allowing for the fact that in certain states the income tax rate applies to individual incomes only, while in others it applies to corporate in- comes, that in a few states only income from specified sources has been taxed, that certain states tax residents only while others tax in addition the income derived within the state by non-residents, it is nevertheless clear that such a tax as that of Massachusetts, which yields, from specified incomes only, an amount approximately equal to one third of that collected by the federal government, is a satisfactory fiscal measure; while such a state as Mississippi, which, from a tax upon all individual incomes, gains only about 1½ per cent of the amount collected through the federal channels, is justified in regarding the measure as one which on financial grounds is not worth keeping on the statute books. An estimate of the success of the taxes on the basis of their relation to the tax system of the respective states, and as gauged by the cost of collection, is not so readily made. No one of these states exactly resembles another with respect to the classes of receipts included in the state fund. Moreover, the intentions of the legislators obviously differ. In Massachusetts, for example, the tax is a substitute for that on intangible personal property; in Delaware, on the other hand, the tax is apparently intended only as a superstructure. Few states emphasize the cost of collection, or have the necessary figures in such form that it can be computed on a basis comparable with that of Wisconsin, for example. In so far as the cost is known, it presents the amount of variation which is to be expected under the diverse systems-from almost 4 per cent in Virginia to slightly more than 1 per cent (on assessments) in Wisconsin. State income taxes are still so limited in application that the fiscal results cannot yet be used in proof positive of success or failure. The analysis indicates, however, that success, measured in terms of relatively large amounts of state receipts from this source, is possible, but is largely conditioned by an accurate adaptation of the rates to the types of incomes represented in the state in question, and by the use of specialized and centralized administrative mechanism. [ABSTRACT FROM AUTHOR]