New York City’s sick employees will now get paid days off thanks to Mayor Bill de Blasio and the City Council. On March 20, de Blasio signed the Earned Sick Time Act (ESTA) into law, which will give workers in businesses with five employees or more the opportunity to earn up to 40 hours of paid sick leave per year—and contains other requirements that apply to smaller employers, too.

The law, which kicks in on April 1, will give half a million more employees paid sick leave in New York. And although many employers will have a six-month safe period before penalties for noncompliance begin, the city’s employers will have work on their hands to make assessments and get administrative details in order, said Marc Mandelman, senior counsel at Proskauer Rose in New York, and cohead of the firm’s Employment Law Counseling and Training Group. “One of the things about this law is that it is very complicated to implement and has a lot of detailed provisions,” he said.