This paper surveys the major issues regarding the transferability of tax losses upon a change of control. Whether tax losses should be transferable or not depends on whether the market for corporate control is efficient or not. If there are too few efficiency-enhancing takeovers, then takeovers should be - subsidized - . If, on the contrary, there are too many takeovers (from an efficiency point of view), then takeovers should somehow be taxed. In either case, the transferability of tax losses may be an instrument for doing so. Three aspects are considered: (1) whether tax losses should be transferred upon a change of control or not, (2) whether the transfer should be restricted to the same line of business or not, and (3) whether losses should be used at the same speed at which they were (to be) used pre-merger or not. These issues are then discussed in the context of managerial control, product market competition, financing decisions, and investment decisions and risk-taking.