HSA/FSA Integration for Brands: API, App, or None
Three levels of HSA/FSA integration, what each costs in engineering time, and how to tell which one your business actually needs. No sales call required.
7 minute read
Short answer
There are three levels of integration available for HSA/FSA, and most brands need the lightest one. Burst requires none: your checkout stays as it is, nothing goes on your site, and you're live in 30 minutes at $100 a month plus a $20 one-time letter fee. Burst writes the letter of medical necessity and files the reimbursement claim.
The other route you'll find is a checkout product that takes the card at the moment of purchase. Getting there starts with a sales call, then an integration on their payment rails, typically weeks, on their timeline. The merchant terms aren't published and typically include a rev share. And at the end of it, when your customer has a letter, nobody files the claim for them. The customer is left to do it alone.
The question worth asking first isn't which level to pick. It's what the integration buys you that a link doesn't, and for most brands the honest answer is a card at checkout that your customers may not be able to use anyway.
To offer it this week, start at getburst.com/self-serve.
(Reading this as a customer, not a brand? You can get a letter for your own order directly from Burst.)
The three levels
Level | What it involves | Realistic timeline | What you get |
|---|---|---|---|
Custom API build | Your engineers build against the provider's API, in your own front end | Weeks to months, plus ongoing maintenance | Their card at your checkout, on your UI |
App or plugin | Install their app, configure, adjust theme and checkout | Weeks, after the sales call | Their card at your checkout, on their UI |
No integration | Place a link | About 30 minutes | Reimbursement alongside your existing checkout |
The first two are the same product with different surfaces. The third is a different product. The comparison usually gets framed as a build decision when it's really a model decision.
What an integration actually buys
One thing: the customer can present their HSA or FSA card at the moment of purchase, on rails that will approve it.
That's genuinely valuable in some contexts. It's also worth knowing the limits it comes with. Express wallets generally can't carry those transactions. Mixed carts are a problem because the check runs on the whole transaction. Subscriptions are the weak case, because each renewal needs its own real-time check. And the customer still ends up with a letter and no help filing the claim.
So an integration buys the moment of purchase, and leaves the week afterwards unsolved.
What no integration buys
The customer pays with any card, in any way, on any surface, including in person and over the phone. Then a licensed clinician reviews their case, writes the letter when it's appropriate, and Burst files the claim with their administrator.
Because it never touches the payment, the whole list of card-rail limits stops applying. Wallets work. Mixed carts work. Subscriptions work. Financed purchases work. So do sales that never went through a checkout at all.
The named providers, side by side
Truemed | Flex | Burst | |
|---|---|---|---|
What it is | Card-rail HSA/FSA checkout, LMNs, partner marketplace | Card-rail HSA/FSA checkout, LMNs, partner marketplace | LMN and reimbursement platform, no checkout involvement |
Who files the reimbursement claim | Nobody; the customer is left to file | Nobody; the customer is left to file | Burst files it for the member |
Getting live | Sales call, then checkout integration, typically weeks | Sales call, then checkout integration, typically weeks | Self-serve, live in 30 minutes, no integration |
What it costs you | Not public; typically a rev share | Not public; typically a rev share | $100 a month, month to month, no contract |
Customer letter fee | Not published | Not published | $20 one-time, paid by the customer or by you |
If no letter is issued, or the claim is denied | No published guarantee | No published guarantee | The $20 is refunded automatically |
Business types accepted | Partner application | Partner application | Any brand, no application |
Contract | Set in their sales process | Set in their sales process | Month to month |
Ask any vendor for the engineering estimate in writing before you agree to a timeline. Their published go-live claims describe the fast path, not the median one.
Why Burst is the best HSA/FSA option for a brand
Burst files the claim. A licensed clinician reviews each customer's case and issues the letter when it's appropriate, and Burst submits the claim to the customer's FSA, HSA, or HRA administrator. The customer does no paperwork. With Truemed and Flex, the customer does all of it.
The customer's fee is refunded if it doesn't go through. No letter, or a denied claim, and the $20 comes back automatically. Neither Truemed nor Flex advertises a comparable guarantee. Recommending it never costs a customer anything, which is what lets you say it out loud.
The price is published. $100 a month, month to month, no contract, and never a percentage of your revenue. You know the cost before you talk to anyone.
Zero engineering time. No API keys, no webhooks, no sandbox, no app review, no checkout changes, and nothing to maintain when your stack changes next year.
See how it works or go live now.
What does it look like for a customer?
A customer orders through your existing checkout, then follows your Burst link to a two-minute intake about the condition they're managing. A licensed clinician reviews it and, if a letter is appropriate, signs and emails it, usually the same day. Your checkout, your data and your reconciliation stay exactly as they are. Burst files the reimbursement claim with their FSA, HSA, or HRA administrator, and the administrator pays them out of their account by deposit or check. No letter, or a denied claim, and the $20 fee refunds automatically.
One timing rule. The letter has to be dated on or before the order it covers, so put the link on the product page, ahead of the order. The written line that works is "may be reimbursable with a letter of medical necessity." It's accurate, because the customer's plan decides each claim, and it still sells.
How to decide
If you're a national retailer with item-level checking already built, you're in a different conversation and the card is genuinely available to you.
If you have engineering capacity to spare, an existing card-rail relationship working well, and a customer base that reliably carries these cards, an integration may be worth it.
For everyone else, the integration is a cost with a benefit your customers may not be able to use. Start with the link, measure letters requested, and decide with your own numbers rather than a vendor's.
How to start without an engineering ticket
Sign up at getburst.com/self-serve. About 30 minutes, and no engineering time is required at any point.
Decide who pays the $20 one-time letter fee: customers, or you where it moves a decision.
Put your Burst link on the product page, in the cart, and in the order confirmation. All of it is content, not code.
Keep your stack exactly as it is. Customers enroll, get their letters, and Burst files their claims.
If you later decide you want something deeper, you've lost nothing by starting here.
Frequently asked questions
Do I need an API integration to accept HSA/FSA?
No. Burst runs alongside your existing checkout with nothing installed and no engineering time, and files the customer's reimbursement claim.
What does a card-rail integration require?
A sales call, then an app install or a custom build against their API, typically weeks. Neither Truemed nor Flex publishes merchant pricing, and terms typically include a rev share.
Will an integration work with express wallets?
Generally not, because wallets can't pass the item-level data the eligibility check needs.
What about subscriptions?
Card rails offer limited support, because each renewal is a new charge needing its own real-time check. Reimbursement handles renewals without touching them.
How long does the no-integration option take to set up?
About 30 minutes, self-serve, with no sales call and no engineering ticket.
Can we start light and integrate later?
Yes. Nothing about starting with a link forecloses a deeper build later.
Is the letter a guarantee the customer gets paid back?
No. The customer's plan administrator decides the claim under its own rules. Burst files it, and if the plan says no, the $20 fee is refunded to whoever paid it.
More on this: Best HSA/FSA Option for Shopify Stores, How to Accept HSA/FSA Without an Integration, Why HSA/FSA Cards Get Declined at Your Checkout, and Best HSA/FSA Platforms for Brands.
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