Locate 1.2 million people. Find even the thousands of them who don’t speak English or don’t have a place to live. Get them to fill out a 26-page application. Process those forms. And get it done by the end of the year.

That is the unprecedented mandate facing state officials this year: to scour the rolls of MassHealth, the state’s Medicaid program for low-income people, and make sure that all the enrollees are still eligible.

Officials stumbled at first with an attempt to reenroll 500,000 people in just three months. There were long waits at the MassHealth call center and long lines at the community health centers. Thousands of other recipients simply failed to do anything. In the end, officials extended deadlines, added staff, and changed policies.