> This page is for version v1 (default).
> For other versions, use one of these documentation indexes:
> - v1 (default): https://developers.truemed.com/v-1/llms.txt

> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://developers.truemed.com/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://developers.truemed.com/_mcp/server.

# Core concepts

> How Truemed's HSA/FSA payment model works and the key terms used throughout these docs.

This page explains how Truemed works and defines the terms you'll see throughout these docs.
If you're new to HSA/FSA payments, read this before choosing an integration path.

## What Truemed does

Truemed enables your customers to spend pre-tax **HSA** (Health Savings Account) and **FSA**
(Flexible Spending Account) dollars on eligible health and wellness products. Many products
require a **Letter of Medical Necessity (LMN)** from a licensed provider, while others are
**pre-approved** and need no LMN at all. Truemed determines which is which, runs any required
eligibility screening, generates the LMN when one is needed, and handles the compliance
paperwork—so your customers get tax-free spending and you don't have to build any of it.

## The two flows

Truemed supports two distinct models. They solve the same problem—letting customers use HSA/FSA
funds—but the customer experience and your integration differ. Don't conflate them.

### Pay at checkout

The customer pays **directly with their HSA/FSA card** as part of your normal checkout. Truemed
determines eligibility mid-checkout, collects the payment, and notifies you of the final status
so you can fulfill the order. [How a Truemed checkout works](#how-a-truemed-checkout-works) below
walks through each step.

Most integrations on this site—Shopify, WooCommerce, Stripe, and custom/iFrame—implement this
flow. See [How Truemed Checkout Works](/guides/setup/api/payment-sessions/how-truemed-checkout-works) for the
end-to-end sequence.

### Post-checkout reimbursement

The customer pays **as usual with a regular card**, then gets reimbursed afterward.

1. The customer completes a normal purchase.
2. Truemed issues a qualified LMN and an itemized receipt.
3. The customer submits these to their HSA/FSA administrator and is reimbursed from their
   pre-tax funds.

This flow requires no change to how payment is collected at checkout—the value is the qualified
documentation Truemed provides.

## Product eligibility

Not every product qualifies for HSA/FSA spending the same way. Truemed sorts the items you sell
into two eligibility categories, and the category determines the customer's checkout experience:

* **[Pre-approved](/guides/get-started/eligibility-and-qualifying-businesses#eligibility-outcomes)** — Eligible for HSA/FSA purchase
  **without an LMN**. Customers buy these directly with HSA/FSA funds—no health survey, faster checkout.
* **[Eligible with LMN](/guides/get-started/eligibility-and-qualifying-businesses#eligibility-outcomes)** — Qualify **only if** the customer
  completes a medical-necessity health survey and receives an LMN, which Truemed generates as part of the flow.

If a cart mixes the two, the health survey appears only because of the LMN-eligible items.

> **Note**
>
> Truemed classifies the products you submit—see the
> [Product Catalog](/guides/setup/api/product-catalog/overview) overview for how eligibility is determined
> and kept up to date.

## Key terms

| Term                                  | What it means                                                                                                                                                                          |
| ------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **HSA / FSA**                         | Tax-advantaged accounts customers can use for qualified medical expenses.                                                                                                              |
| **Eligibility**                       | Whether a given product can be purchased with HSA/FSA funds. Truemed determines this.                                                                                                  |
| **Letter of Medical Necessity (LMN)** | Provider documentation that qualifies a purchase for HSA/FSA spending. Truemed generates it.                                                                                           |
| **Pre-approved**                      | A product that's HSA/FSA-eligible with no LMN required—no health survey, faster checkout.                                                                                              |
| **Eligible with LMN**                 | A product that qualifies only when the customer completes a health survey and receives an LMN.                                                                                         |
| **Health survey**                     | A short questionnaire the customer completes so Truemed can assess eligibility.                                                                                                        |
| **Payment session**                   | The Truemed-hosted flow a customer is redirected to in order to verify eligibility and pay. The core object behind the pay-at-checkout integrations.                                   |
| **Authorization & capture**           | Funds can be authorized first and captured later ([manual capture](/guides/overview/glossary#manual-capture)), or [captured immediately](/guides/overview/glossary#immediate-capture). |

## How a Truemed checkout works

No matter which integration you use, the customer experience follows the same path:

#### The customer checks out with Truemed

At checkout, the customer chooses to pay with their HSA/FSA through Truemed.

#### They're redirected to a Truemed session

The customer is sent to a secure, Truemed-hosted session to complete the next steps.

#### They qualify via a health survey

The customer completes a short health survey to determine eligibility for HSA/FSA spending.

#### They enter their HSA/FSA card

Once qualified, the customer pays with their HSA/FSA card.

#### Truemed collects the payment

Once the LMN is approved, Truemed charges the customer's HSA/FSA card and notifies you that the
payment is complete so you can fulfill the order.

## Where to go next

* **[Choose your integration](/guides/get-started/choose-your-integration)** — jump to the setup guide for your stack.
* **[Glossary](/guides/overview/glossary)** — quick definitions for every term in these docs.
* **[How Truemed Checkout Works](/guides/setup/api/payment-sessions/how-truemed-checkout-works)** — the full pay-at-checkout model.
* **[Accept Your First Payment](/guides/setup/api/payment-sessions/accept-your-first-payment)** — the fastest path to a working payment flow.

## Want to skip ahead?

#### [API Reference](/api-reference)

Complete reference for every endpoint, with request and response details and SDK snippets.

#### [Marketing Resources](/marketing/overview)

Playbooks, templates, and assets for promoting HSA/FSA payments across your site, email, SMS, and ads.