E-Verify matches job applicants’ Social Security numbers and other identification against a national database kept by U.S. Citizenship and Immigration Services, a federal agency under Homeland Security. Those who return a mismatch are deemed to be unauthorized to work. The government’s effort to mandate E-Verify’s use is part of a broader immigration overhaul by federal lawmakers that could legalize most of the estimated 11 million undocumented immigrants living in the U.S. That has the potential to level the playing field for job applicants and help employers struggling with E-Verify mismatches. Meanwhile, though, a close look at early E-Verify system users illustrates some of the challenges facing business owners who liked the old way-generally, simply asking job seekers to fill out federal paperwork, known as I-9 forms, and trusting that any proof of identity they provide is legitimate. Specifically, since using the E-Verify system, many owners of small firms say it has become far more difficult to fill open positions, and recruitment costs are rising. Others point out that using the system requires some employers to hire extra staff or upgrade computer equipment to manage the online process. The system is strictly voluntary for most other employers across the country. But that may change soon.