This paper investigates incentives for firms to increase output above the activity level thresholds (ALTs) in order to obtain more free allowances in the EU Emissions Trading Scheme. While ALTs were introduced in order to reduce excess free allocation to low-activity installations, for installations operating below the threshold, the financial gain from increasing output to reach the threshold may outweigh the costs. Using installation level data for 246 clinker plants, we estimate the effect of ALTs on output decisions. The ALTs induced 5.8Mt of excess clinker production in 2012 (4% of total EU output), which corresponds to 5.2Mt of excess CO2 emissions (over 5% of total sector emissions). As intended, ALTs do reduce overallocation (by 6.6...