MIT economist Jonathan Gruber examines how the corporate tax code shapes business investment decisions in this session from 14.41, Public Finance and Public Policy. The lecture works through the mechanics of corporate taxation, including how firms weigh the cost of capital against expected after-tax returns, and how depreciation rules and investment incentives can push firms toward or away from spending on new equipment and projects. Gruber uses the standard economic framework for the user cost of capital to show how tax policy changes effectively raise or lower the price of investing, then connects this to real policy debates over accelerated depreciation and investment tax credits. As with the rest of the course, the session builds on public finance theory covered earlier in the semester and assumes some familiarity with basic tax concepts. Delivered as a 73 minute classroom lecture with Gruber working through diagrams and formulas at the board.