True/False

1)Two notable trends in tax revenue sources is that social security taxes have decreased gradually while corporate income taxes have increased gradually over the last fifty years.

2. If a progressive tax rate system is used, as a taxpayer's taxable income decreases, a progressively higher rate of tax is applied.

3. The marginal tax rate measures the tax rate applicable to the next dollar of income or deduction for a taxpayer.

4. Using retroactive dates for changes in the tax law violates the objective of certainty as identified in Adam Smith's "canons of taxation."