21st Century Investment Act of 201 7 This bill amends the Internal Revenue Code to: (1) modify the tax credit for increasing research activities to allow an increased 25% tax credit rate for expenses for research, substantially all of which occurs in the United States; and (2) increase to 15%, through 2024, the tax deduction for income attributable to domestic manufacturing production activities for which substantially all of the research and development occurred in the United States.