to push women back into unpaid or lower paid work after their substantial economic contributions during World War II, led to the override of Truman's double veto. Fictional income splitting is strongly opposed by people in two-earner marriages, and especially by those in Shared Earning/Shared Parenting Marriages. U.S. economists Betsey Stevenson and Justin Wolfers are among those who oppose it. The opposition also comes from those who see this type of taxation contributing to problems of child neglect, particularly by fathers, family breakdown, unequal pay for equal work problems for women, poverty in general, and the feminization of poverty, particularly in older women. Germany In Germany, income splitting involves two aspects. First, if married couples file jointly, their total tax liability is determined by twice the tax liability of applying half the total taxable income. Let and denote each spouse's taxable income. Defining the tax schedule, the tax due for couples is computed by . The splitting advantage increases if both partners have unequal incomes. Another consequence is a high marginal tax rate for the secondary earner, as the secondary earner indirectly pays the marginal tax rate of the higher-earning spouse. The second aspect involves the Withholding tax (Lohnsteuer) which is paid on employment income. Family taxation implies that married couples may split the total basic exemption (Grundfreibetrag). This is done via choosing the appropriate tax bracket (Steuerklasse). The higher-earning spouse predominantly opts for Steuerklasse III to claim both exemptions, while the lower-earning spouse will be taxed without exemption (Steuerklasse V). Both arrangements are widely considered to create an incentive for unequal employment within married couples in Germany, providing one cause for low labor force participation among married women. Canada Income splitting was not a part of Canada's tax system until the 21st century. From the introduction of income tax, Canadian households were almost exclusively deemed to be single income households. In 1962, a Royal Commission on Taxation was initiated under Kenneth Carter by Prime Minister John Diefenbaker to examine and to recommend improvements to the federal tax system. The report declared "that fairness should be the foremost objective of the taxation system; the existing system was not only too complicated and inefficient, but under it the poor paid more than their fair share while the wealthy avoided taxes through various loopholes." From the Carter commission's report: "We conclude that the present system is lacking in essential fairness between families