HSA/FSA
How Flex Makes HSA/FSA Subscriptions Seamless and Compliant
Subscriptions are one of the biggest growth drivers in eCommerce, but for HSA/FSA products, they’ve historically been difficult to manage. Flex makes it easy to offer recurring, compliant payments across every channel.
November 5, 2025
Teddy Butz
Director of Product & Partner Marketing
Overview
Overview
Overview
Subscriptions are one of the biggest growth drivers in eCommerce, but for HSA/FSA-eligible products, compliance requirements have made recurring payments difficult to manage. Flex offers a powerful, robust subscriptions solution that supports always-eligible and dual-purpose products across platforms. Let’s dive in.
Why Subscriptions Matter for Health & Wellness Brands
By combining the retention power of subscriptions with the tax savings of HSA/FSA, brands can unlock significant growth potential:
Higher retention: Brands using subscriptions see a 7–10% increase in retention compared to standard payment methods.
Built-in compliance: Flex validates eligibility at every renewal, keeping merchants fully compliant with IRS rules.
Flexible setup: Choose whether to integrate via our API or Shopify. Flex can manage billing or you can integrate it into your existing subscription engine.
What the Subscription Experience Looks Like
From the shopper’s perspective, subscribing with Flex feels just like any other subscription, with the added benefit of using pre-tax dollars. Customers can either pay directly with their HSA/FSA card or use a regular card and complete a quick reimbursement flow after checkout. In both cases, Flex ensures a seamless, compliant checkout at every renewal.
For direct HSA/FSA subscription payments:
Customers pay with their HSA or FSA card at checkout for both always-eligible and dual-purpose products. If required, Flex automatically generates a Letter of Medical Necessity to stay compliant. Each renewal is validated seamlessly to ensure ongoing eligibility.
For reimbursement-based subscriptions:
If customers can’t use their HSA/FSA card directly, Flex enables a smooth reimbursement experience after purchase. Shoppers pay with a regular credit card, then complete a short post-purchase flow to receive the documentation they need for reimbursement. The process stays compliant and convenient from start to finish.
In both cases, the experience is seamless: customers can get access to their HSA/FSA dollars while Flex handles the compliance behind the scenes.
Enabling Subscriptions with Flex: Key Features
We include a number of features designed to make recurring HSA/FSA payments seamless for both merchants and shoppers.
1. Automated Renewals and Eligibility Validation
Every renewal is automatically revalidated for eligibility to ensure IRS compliance. For products that require a Letter of Medical Necessity (LMN), Flex generates and revalidates the letter at renewal, pausing the subscription if needed until compliance is confirmed.
2. Mid-Cycle Upgrades, Downgrades, and Line-Item Control
Flex supports advanced subscription management features like mid-cycle plan upgrades and downgrades, along with granular line-item control. Merchants can add or remove eligible items mid-term without interrupting billing, offering a more flexible and customer-friendly experience.
3. Subscription Insights in the Dashboard
The Flex Dashboard provides complete visibility and control over your subscriptions. You can:
View all active subscriptions
Track purchase history and order details to understand customer behavior
Update, cancel, or refund subscriptions directly from the dashboard
Identify upsell and retention opportunities with full performance analytics
4. Manage Subscriptions Your Way
Flex gives you control over how your subscriptions are handled. Flex can manage billing, renewals, and eligibility validation automatically for a fully managed experience. Or if you prefer to use your own subscription engine, you can trigger off-session renewal payments through our API.
5. Cross-Platform Support
Flex works wherever you sell, whether through our API (web or in app), or Shopify.
Web (API): Power your own checkout and subscription logic while Flex automates billing and compliance.
In App (via Flex and our RevenueCat integration): Bring compliant subscription payments to iOS and Android apps using the Flex API integrated with RevenueCat.
Shopify: Offer recurring HSA/FSA-eligible products through Shopify’s native checkout.
Flex brings together payments, compliance, and analytics in one place, helping merchants stay compliant and grow recurring revenue through better data.
In Conclusion
Health and wellness brands thrive when customers build lasting habits. With Flex’s subscription support, you can make those habits easier and compliant for every shopper using their HSA or FSA dollars.
To learn more about enabling subscriptions with Flex, visit our developer documentation, or connect with our team.
Subscriptions are one of the biggest growth drivers in eCommerce, but for HSA/FSA-eligible products, compliance requirements have made recurring payments difficult to manage. Flex offers a powerful, robust subscriptions solution that supports always-eligible and dual-purpose products across platforms. Let’s dive in.
Why Subscriptions Matter for Health & Wellness Brands
By combining the retention power of subscriptions with the tax savings of HSA/FSA, brands can unlock significant growth potential:
Higher retention: Brands using subscriptions see a 7–10% increase in retention compared to standard payment methods.
Built-in compliance: Flex validates eligibility at every renewal, keeping merchants fully compliant with IRS rules.
Flexible setup: Choose whether to integrate via our API or Shopify. Flex can manage billing or you can integrate it into your existing subscription engine.
What the Subscription Experience Looks Like
From the shopper’s perspective, subscribing with Flex feels just like any other subscription, with the added benefit of using pre-tax dollars. Customers can either pay directly with their HSA/FSA card or use a regular card and complete a quick reimbursement flow after checkout. In both cases, Flex ensures a seamless, compliant checkout at every renewal.
For direct HSA/FSA subscription payments:
Customers pay with their HSA or FSA card at checkout for both always-eligible and dual-purpose products. If required, Flex automatically generates a Letter of Medical Necessity to stay compliant. Each renewal is validated seamlessly to ensure ongoing eligibility.
For reimbursement-based subscriptions:
If customers can’t use their HSA/FSA card directly, Flex enables a smooth reimbursement experience after purchase. Shoppers pay with a regular credit card, then complete a short post-purchase flow to receive the documentation they need for reimbursement. The process stays compliant and convenient from start to finish.
In both cases, the experience is seamless: customers can get access to their HSA/FSA dollars while Flex handles the compliance behind the scenes.
Enabling Subscriptions with Flex: Key Features
We include a number of features designed to make recurring HSA/FSA payments seamless for both merchants and shoppers.
1. Automated Renewals and Eligibility Validation
Every renewal is automatically revalidated for eligibility to ensure IRS compliance. For products that require a Letter of Medical Necessity (LMN), Flex generates and revalidates the letter at renewal, pausing the subscription if needed until compliance is confirmed.
2. Mid-Cycle Upgrades, Downgrades, and Line-Item Control
Flex supports advanced subscription management features like mid-cycle plan upgrades and downgrades, along with granular line-item control. Merchants can add or remove eligible items mid-term without interrupting billing, offering a more flexible and customer-friendly experience.
3. Subscription Insights in the Dashboard
The Flex Dashboard provides complete visibility and control over your subscriptions. You can:
View all active subscriptions
Track purchase history and order details to understand customer behavior
Update, cancel, or refund subscriptions directly from the dashboard
Identify upsell and retention opportunities with full performance analytics
4. Manage Subscriptions Your Way
Flex gives you control over how your subscriptions are handled. Flex can manage billing, renewals, and eligibility validation automatically for a fully managed experience. Or if you prefer to use your own subscription engine, you can trigger off-session renewal payments through our API.
5. Cross-Platform Support
Flex works wherever you sell, whether through our API (web or in app), or Shopify.
Web (API): Power your own checkout and subscription logic while Flex automates billing and compliance.
In App (via Flex and our RevenueCat integration): Bring compliant subscription payments to iOS and Android apps using the Flex API integrated with RevenueCat.
Shopify: Offer recurring HSA/FSA-eligible products through Shopify’s native checkout.
Flex brings together payments, compliance, and analytics in one place, helping merchants stay compliant and grow recurring revenue through better data.
In Conclusion
Health and wellness brands thrive when customers build lasting habits. With Flex’s subscription support, you can make those habits easier and compliant for every shopper using their HSA or FSA dollars.
To learn more about enabling subscriptions with Flex, visit our developer documentation, or connect with our team.
Flex is the easiest way for direct to consumer brands and retailers to accept HSA/FSA for their products. From fitness and nutrition, to sleep and mental health, Flex takes a holistic view of healthcare and enables consumers to use their pre-tax money to do the same.