We examine the costs and benefits of proactive financial reporting enforcement by the UK Financial Reporting Review Panel. Enforcement scrutiny is selective and varies by sector and over time, yet can be anticipated by auditors and companies. We find evidence that increased enforcement intensity leads to temporary increases in audit fees and more conservative accruals. However cross-sectional analysis across market segments reveals that audit fees increase primarily in the less-regulated AIM segment, and especially those AIM companies with a higher likelihood of financial distress and less stringent governance. On the contrary, less reliable operating asset-related accruals are more conservative in the Main segment, and in particular those Main companies with stronger incentives for higher financial reporting quality. Overall, our study indicates that financial reporting enforcement generates costs and benefits, but not always for the same companies.