Flex + RevenueCat: Accept HSA/FSA payments for in-app subscriptions

We’re excited to announce a new integration with Flex, enabling developers to accept HSA (health spending account) and FSA (flexible spending account) payments for in-app subscriptions for the very first time.

This update lets health and wellness apps offer compliant, tax-advantaged payment options, managed through RevenueCat and powered by Flex’s HSA/FSA technology.

Together, we’re unlocking a new, compliant revenue stream for developers and a smoother checkout experience for users eager to use their pre-tax dollars on eligible digital health products.

Why this mattersCopy link to this section

Until recently, Apple’s in-app purchase (IAP) requirements limited developers to billing systems that didn’t support HSA or FSA cards.

For digital health apps, that created friction on both sides:

• Users couldn’t apply their pre-tax benefits to eligible subscriptions.
• Developers lost conversions or forced users into manual reimbursement flows.

Now, with Apple supporting external billing in the US, developers using RevenueCat + Flex can securely accept HSA/FSA payments while maintaining all the benefits of RevenueCat’s cross-platform subscription management, analytics, and entitlements.

The result: more compliant payment flexibility, better user experience, and higher conversion from a previously untapped payment channel.

How it worksCopy link to this section

The integration connects Flex’s HSA/FSA payment processing with RevenueCat’s subscription infrastructure.

Developers can activate it in just two steps inside the RevenueCat dashboard — no major engineering lift required.

Once enabled:

• Flex ensures every transaction meets IRS and plan requirements.
• RevenueCat handles subscription renewals, trials, analytics, and entitlements across all platforms.

That means developers can launch new payment options fast — while keeping everything in sync with their existing billing systems (like Stripe or IAP).

What developers are seeingCopy link to this section

Early adopters like Ladder, the strength training app, have already seen measurable impact:

“The Flex integration through RevenueCat made it simple for Ladder to offer subscriptions via HSA and FSA cards — a major unlock for our users and an effective new growth lever.

We launched an email campaign educating potential customers about HSA/FSA eligibility using Flex’s marketing guide, and within a few weeks saw over 500 annual subscribers check out using their benefits.

From a technical standpoint, Flex’s seamless, native integration with RevenueCat functions just like our Stripe and IAP integrations — keeping our data and entitlements consistent while enabling a smooth experience across all of our purchase channels.” — Ryan Mott, VP of Data Product at Ladder

For developers, this opens access to over $100 billion in annual U.S. HSA/FSA spending — and makes it possible to capture that demand directly from their apps.

Available nowCopy link to this section

The Flex + RevenueCat integration is available today for all Flex and RevenueCat customers.

👉 Get started here and start accepting HSA/FSA payments in-app in minutes.