§ 8. #Exemptions and stoppage at source#. There are various exemptions, the first being that of $3000 on every individual income and of $4000 on the aggregate income of husband and wife living together.[11] Among other exceptions are sums paid for taxes (except assessments for local benefits), necessary business expenses, losses sustained, and (for the normal tax only) those parts of individual incomes derived from corporations which have paid the tax on them. The difficulty of getting an honest and complete assessment of incomes is great. All taxation is deemed by the taxpayer to be "inquisitorial" in some degree, and this is particularly true of an income tax. In England had been developed the plan called "stoppage at source." In our law the taxation of corporations at the rate of the normal tax, while requiring them to report the names of those receiving dividends and interest payments, affords an ingenious way of checking up the returns of individuals in respect to a class of investments which is steadily increasing in importance. § 9. #The graduation principle#. The most disputed feature of the income tax is the principle of graduation, or of progression. It is upheld in part because in this case it but offsets _regression_, that is relatively heavier taxation on the smaller incomes, in the case of the other kinds of taxes (tariff, property taxes, etc.). It is urged further that those of larger incomes, especially the largest, have marked advantages over others in making investments. Further it is urged that the higher the income the less does a certain rate cut into "the amount necessary for good living" (as was said in Congressional debate). This is in accord with the psychological principles of choice, of value, and of diminishing gratification. Finally, there is a widespread approval of the progressive rate just because it in so far acts as a leveling influence upon fortunes. The "additional" tax is already important fiscally, yielding over one-half of the total paid by individuals and one-fourth of the total from corporations and individuals. The income tax returns for the first ten months of the law (March to December, 1913) showed 356,598 taxable individual incomes, equal to about 1 per cent of the taxable population (considering minors to be usually not taxable). Even this proportion, small as it is, is much larger than that of the European countries having a general income tax.