In Shanghai’s Putuo District, a community restaurant recently posted a Help Wanted sign on its door, encouraging men aged 60 and up and women aged 55 and up to apply for a job with “generous pay.” Younger people need not apply, it said.

The ad highlights a significant transformation taking place in Chinese cities that could negatively impact businesses. Chinese authorities say that starting on Sept. 1, they will fully enforce long-standing social insurance contribution rules, wiping out a gray zone that allows many employers to evade payments and employees to opt out.