Announcements
Flex + RevenueCat: Enabling HSA/FSA Payments for In-App Subscriptions
Flex and RevenueCat have partnered to bring compliant HSA/FSA payment acceptance into iOS, Android, and web apps. This integration helps developers capture a new revenue stream from users who want to pay for digital health subscriptions with their pre-tax dollars.
November 14, 2025
Sam O'Keefe
Co-founder & CEO of Flex
Overview
Overview
Overview
Today, we’re excited to announce our partnership with RevenueCat, making it possible for health and wellness apps to accept HSA/FSA payments for in-app subscriptions for the very first time. This integration enables compliant, tax-advantaged payment options inside their iOS, Android, and web apps—seamlessly managed through RevenueCat’s subscription infrastructure and powered by Flex’s HSA/FSA payments.
Together, we’re helping developers capture a new revenue stream from customers eager to use their pre-tax dollars for eligible digital health products.
Why This Matters
Until now, Apple’s strict in-app purchase rules required developers to process payments through its own billing system (IAP), which doesn’t natively support HSA or FSA cards.
For health and wellness apps, this created a major roadblock. Consumers wanted to use pre-tax funds for eligible purchases, but there was no compliant way to do it. Merchants lost conversions, and users faced manual reimbursement processes after checkout.
With Apple now allowing external billing, Flex + RevenueCat opens the door for developers to capture that lost revenue, securely and at scale.
How It Works
The integration connects Flex’s compliant HSA/FSA payment processing with RevenueCat’s subscription management, analytics, and entitlement tracking.
Developers can activate it in just two steps inside the RevenueCat dashboard, with no major engineering lift. Flex ensures every transaction meets IRS and plan requirements, while RevenueCat handles renewals, trials, and cross-platform sync.
Early Results
Early adopters are already seeing results. Ladder, a leading fitness training app, launched the integration quickly—giving members the option to subscribe using pre-tax funds and driving incremental revenue from customers who previously couldn’t complete checkout.
“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. Our next step is to embed this option directly into our in-app purchase flow, which we expect will drive even greater adoption.”— Ryan Mott, VP of Data Product at Ladder
The opportunity ahead is massive: U.S. consumers spend over $100 billion annually in HSA/FSA accounts. Flex and RevenueCat now make it possible for wellness developers to tap into that spend directly from their apps.
Available Today
The Flex + RevenueCat integration is now available to all Flex and RevenueCat customers. Activate it in minutes and start accepting HSA/FSA payments in-app. Get started here.
Today, we’re excited to announce our partnership with RevenueCat, making it possible for health and wellness apps to accept HSA/FSA payments for in-app subscriptions for the very first time. This integration enables compliant, tax-advantaged payment options inside their iOS, Android, and web apps—seamlessly managed through RevenueCat’s subscription infrastructure and powered by Flex’s HSA/FSA payments.
Together, we’re helping developers capture a new revenue stream from customers eager to use their pre-tax dollars for eligible digital health products.
Why This Matters
Until now, Apple’s strict in-app purchase rules required developers to process payments through its own billing system (IAP), which doesn’t natively support HSA or FSA cards.
For health and wellness apps, this created a major roadblock. Consumers wanted to use pre-tax funds for eligible purchases, but there was no compliant way to do it. Merchants lost conversions, and users faced manual reimbursement processes after checkout.
With Apple now allowing external billing, Flex + RevenueCat opens the door for developers to capture that lost revenue, securely and at scale.
How It Works
The integration connects Flex’s compliant HSA/FSA payment processing with RevenueCat’s subscription management, analytics, and entitlement tracking.
Developers can activate it in just two steps inside the RevenueCat dashboard, with no major engineering lift. Flex ensures every transaction meets IRS and plan requirements, while RevenueCat handles renewals, trials, and cross-platform sync.
Early Results
Early adopters are already seeing results. Ladder, a leading fitness training app, launched the integration quickly—giving members the option to subscribe using pre-tax funds and driving incremental revenue from customers who previously couldn’t complete checkout.
“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. Our next step is to embed this option directly into our in-app purchase flow, which we expect will drive even greater adoption.”— Ryan Mott, VP of Data Product at Ladder
The opportunity ahead is massive: U.S. consumers spend over $100 billion annually in HSA/FSA accounts. Flex and RevenueCat now make it possible for wellness developers to tap into that spend directly from their apps.
Available Today
The Flex + RevenueCat integration is now available to all Flex and RevenueCat customers. Activate it in minutes and start accepting HSA/FSA payments in-app. Get started here.
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.