Taxation impacts the BEFORE tax rate of return on investments. The rate of return on investment can be highly impacted by taxation. Short example: Sometimes the rate of return on an IRA, municipal bond, and a Roth can be equal after tax even when the before tax rates of return are different. Taxes and Business Strategy is the name of a course taught by Bob Wyndelts while at ASU. The course is a financial planning and modeling class with taxation included in the modeling.