During 2015, the Smiths and the Joneses both filed joint tax returns. For the tax year ended December 31, 2015, the Smiths’ taxable income was $130,000, and the Joneses had total taxable income of $65,000.

Using the federal tax rates giving in Table 1.2 for married couples filing joint returns, calculate the taxes for both the Smiths and the Joneses.

Calculate and compare the ratio of the Smiths’ to the Joneses’ taxable income and the ratio of the Smiths’ to the Joneses’ taxes. What does this demonstrate about the federal income tax structure?