Slacks implies pants of certain materials which are not part of a suit (jeans are not slacks, and you would not refer to the pair of trousers that came with a suit as slacks.) It is also more common to use slacks to refer to pants worn by women, while men would wear trousers.
Health care safety net providers are those that have a legal mandate or mission to offer medical care to all patients, regardless of their ability to pay, and have a substantial number of patients who are uninsured or on Medicaid.
Millions of uninsured Americans are eligible for premium tax credits to help them pay for health coverage. The premium tax credit is only available to people without another offer of affordable and adequate coverage; in many cases, this will mean that people with employer-sponsored coverage will not be eligible for the premium tax credit.