sources: www.IRS.gov
A health savings account (HSA) is a tax-exempt trust or custodial account that you set up with a qualified HSA trustee to pay or reimburse certain medical expenses you incur. You must be an eligible individual to qualify for an HSA.
No permission or authorization from the IRS is necessary to establish an HSA. When you set up an HSA, you will need to work with a trustee. A qualified HSA trustee can be a bank, an insurance company, or anyone already approved by the IRS to be a trustee of individual retirement arrangements (IRAs) or Archer MSAs. The HSA can be established through a trustee that is different from your health plan provider.