Compliance Hub - Flex Documentation

Accepting HSA/FSA payments means operating inside the IRS’s tax-advantaged account framework. That framework has one non-negotiable principle:

Every HSA/FSA purchase must be substantiated as an eligible medical expense.

The Compliance Hub explains how Flex meets that requirement on your behalf — how we determine what qualifies, how our Inventory Information Approval System (IIAS) gates checkout, and how we work with telehealth partners so dual-purpose products can qualify through a Letter of Medical Necessity.

How Flex Determines Eligibility

The legal foundation — IRC §213(d), Publication 502, and the line between medical treatment and general wellness.

Flex's IIAS

What the IRS requires of an Inventory Information Approval System, who needs one, and how Flex satisfies each requirement.

Telehealth Partnerships

How Flex partners with licensed telehealth providers to build telehealth consultations which fit our merchants’ products and services, and provide Letters of Medical Necessity from telehealth visits.

The three outcomes that drive checkout

Every product in your catalog resolves to one of three checkout behaviors. Everything else in this hub is an elaboration of these:

Outcome	What it means	Customer experience
Auto-substantiated	The product qualifies as a medical expense on its own. Flex approves it through our IIAS.	Pays with an HSA/FSA card. No extra steps.
Dual-purpose (LMN)	The customer can qualify to purchase the product when their primary purpose of purchase is to treat, mitigate, or alleviate a diagnosed condition, but needs documentation.	Completes a telehealth consultation at checkout; a licensed clinician issues a Letter of Medical Necessity upon approval.
Not eligible	The product does not qualify as a medical expense.	Pays with a credit or debit card. In a mixed cart, this portion falls to the remainder.

This documentation explains how Flex applies IRS guidance to product eligibility. It is not legal or tax advice. Employer-sponsored FSA and HRA plans may apply stricter standards than the IRS baseline — see How Flex Determines Eligibility for what that means in practice.

Questions

For eligibility determinations, catalog reviews, or documentation requests, contact compliance@withflex.com. For everything else, reach your dedicated Partner Success Manager or support@withflex.com.

How Flex Determines Eligibility

Flex's IIAS

Telehealth Partnerships

​The three outcomes that drive checkout

​Questions

The three outcomes that drive checkout

Questions