It is okay to just set up a QSEHRA for full-time employees only under this new law. Part-time and seasonal employees can be excluded. But, how does the IRS define part-time and seasonal?

For purposes of determining whether an employee may be excluded from being an eligible employee under the terms of a QSEHRA, “part-time employees” and “seasonal employees” have the meanings set forth in § 1.105-11(c)(2)(iii)(C) of the Income Tax Regulations:

"Part-time employees whose customary weekly employment is less than 35 hours, if other employees in similar work with the same employer (or, if no employees of the employer are in similar work, in similar work in the same industry and location) have substantially more hours and seasonal employees whose customary annual employment is less than 9 months, if other employees in similar work with the same employer (or, if no employees of the employer are in similar work, in similar work in the same industry and location) have substantially more months. Notwithstanding the preceding sentence, any employee whose customary weekly employment is less than 25 hours or any employee whose customary annual employment is less than 7 months may be considered as a part-time or seasonal employee."

Basically, you can't completely arbitrarily set a number of hours worked per week to differentiate between your full-time and part-time employees. But the guidelines for doing so are flexible.

Bottom line: check with your CPA! If you want to set up your QSEHRA for full-time employees only and you aren't sure exactly who to exclude or who qualifies as "full-time," ask your CPA to help you classify your employees according to the definition above.