A cafeteria plan (aka Section 125 plan) is the tax-free structure. An FSA is a benefit within it. A POP is a basic version that only pre-taxes insurance premiums.
POPs
Premium Only Plans (POPs) are simple Section 125 plans that allow employees to pay their share of health insurance premiums with pre-tax dollars. These FAQs explain how POPs work, who can participate, and what employers need to do to stay compliant with IRS rules.