Instant savings when paying with an HSA or FSA card, reflecting the average 30% pre-tax discount on eligible purchases.
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Flex is an HSA/FSA marketplace that connects American consumers with more than 1,000 brands offering health savings account and flexible spending account eligible products. The platform allows shoppers to use pre-tax dollars across categories including skincare, fitness, sleep, nutrition, vision, and women's health.
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About Withflex
Main category
HSA/FSA marketplace
Number of brands
1,000+
Payment methods
HSA/FSA card, credit card, debit card, split payment
Average pre-tax savings
30%
Orders processed
2 million+
Annual unused HSA/FSA funds (US)
$1.5 billion
Customer support
Target audience
US consumers with HSA or FSA benefits
Flex positions itself as a discovery and payment layer for the large segment of Americans who leave HSA and FSA funds unused each year. The platform is aimed at health-conscious consumers who want to stretch their benefit dollars further by purchasing from brands they already recognise, rather than navigating confusing eligibility rules alone. Flex operates at the intersection of health benefits and e-commerce, integrating directly into partner brand checkouts and handling reimbursement documentation such as Letters of Medical Necessity on behalf of customers. The marketplace covers a wide price range across categories, from everyday wellness essentials to premium recovery and sleep technology.
Active promotions
Ready to use with your order at Withflex.
Split payment option at checkout, allowing customers to combine HSA/FSA funds with a regular credit or debit card for a single order.
Example promotion
This is an example of a promotion that could suit this business. It is not a guaranteed active offer or a working discount code. Check the website for current deals.
To the shop
Withflex in the news
Recent updates and background about Withflex, summarised in our own words.
Why HSA/FSA reimbursement often fails customers at the last step
Flex published an analysis of why customers who pay out of pocket for HSA/FSA eligible products frequently fail to get reimbursed, citing complex claim forms and missing Letters of Medical Necessity. Flex addresses this by filing claims and LMNs directly on behalf of customers.
Visit Withflex →Flex introduces MCP integration for AI assistants
Flex launched a Model Context Protocol integration that allows AI tools such as Claude, Cursor, and Codex to connect directly to a Flex HSA/FSA payments account. The feature is aimed at developers and businesses managing HSA/FSA payment workflows.
Visit Withflex →Guide to Lifestyle Spending Accounts and how they work alongside HSA/FSA
Flex published a guide explaining what a Lifestyle Spending Account is, what expenses it covers, and how it differs from an HSA or FSA. The article also covers how consumers can stack LSA and pre-tax benefit dollars on eligible wellness purchases.
Visit Withflex →Summaries by Image Review based on publicly available sources and our own editing. External links may contain affiliate links.
What others ask about Withflex
Answers to the most common questions, based on search behaviour and our own research.
Is Flex (Withflex) a reliable platform to shop with?
Flex has processed more than 2 million orders and works with thousands of brands. The platform handles HSA/FSA payment verification and reimbursement documentation directly, which reduces the administrative burden on customers.
How do I pay with my HSA or FSA card on Flex?
At checkout on a participating brand's website, select 'Flex | Pay with HSA/FSA' as the payment method and enter your HSA or FSA card details. If your card is not available, you can pay with a regular card and Flex will email an itemised receipt for reimbursement.
What happens if my HSA or FSA card is declined?
The most common reason for a declined HSA or FSA card is insufficient funds, as these cards function as debit cards. Customers are advised to check their balance directly with their HSA or FSA administrator.
Do all products on Flex require a Letter of Medical Necessity?
Not all products require a Letter of Medical Necessity. All items listed in the Flex marketplace are HSA/FSA eligible, but some specific products may require a brief telehealth consultation to obtain an LMN before the purchase can be processed.
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