A beaming President Obama on Tuesday signed a $938 billion health care overhaul that included the Senate’s reform bill, the Patient Protection and Affordable Care Act, and a package of changes to the bill through a separate reconciliation bill.

The legislation requires most legal U.S. residents to obtain health insurance and provides government subsidies to help lower-income individuals do so through newly created state health insurance exchanges or marketplaces. It also imposes significant new responsibilities on employers nationwide and could, over time, fundamentally alter the nature of employer-sponsored health care and the workplace itself.