How is the marginal tax rate affected by the presence of rules that reduce current tax deductions by a fraction of incremental income? How is the marginal tax rate affected by the presence of rules...

How is the marginal tax rate affected by the presence of rules that reduce current tax deductions by a fraction of incremental income? How is the marginal tax rate affected by the presence of rules that postpone current tax deductions or tax credits by a fraction of incremental income?