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1099-SA Box 4: FMV on Date of Death (Inherited HSA)

Updated September 29, 2026. Quick answer: Box 4 of Form 1099-SA is used for the death cases the IRS instructions describe. It shows the fair market value of the account on the date the account holder died.

What Box 4 holds

The instruction is short: “Enter the FMV of the account on the date of death.” The 1099-SA instructions read here carry the edition label Rev. December 2026 (the IRS file is dated 22-Dec-2025). FMV means fair market value.

When the account stops being an HSA

For an HSA the instructions say: “If the designated beneficiary is the surviving spouse, the spouse becomes the account holder of the HSA.” and “If the designated beneficiary is not the surviving spouse, the account ceases to be an HSA on the date of the account holder’s death.” In the second case “The FMV of the account as of the date of death is required to be reported in box 4.” Rules for who inherits and what happens next are on the inherited HSA page.

A payment in the year of death, and after

If the payer makes a payment to the beneficiary in the year of death, the instructions have it report the gross distribution in Box 1, code 4 in Box 3 and the date-of-death value in Box 4. For a payment after the year of death, Box 4 is “the FMV of the account on the date of death, reduced by any payments from the HSA made for the decedent’s qualified medical expenses, if paid within 1 year after death”. The payer files “in the year you learned of the death of the account holder”.

Archer and Medicare Advantage MSAs

These follow a similar rule. “If the designated beneficiary is not the spouse or there is no named beneficiary, the account ceases to be an MSA as of the date of death and the fair market value (FMV) on that date is reported.” If the beneficiary is an estate, “enter the estate’s name and TIN in place of the recipient’s on the form.”

Common mistakes

  • Treating the Box 4 figure as the amount you received. It is the account value on the date of death; the payment itself is in Box 1.
  • Assuming Box 4 applies only in the year of death. The instructions also cover a payment made after the year of death.
  • Missing the 1-year reduction. For a later payment, Box 4 is reduced by qualified medical expenses of the decedent paid within a year after death.

Related: 1099-SA Box 3 Distribution Codes 1 to 6 Explained, 1099-SA Box 1 Gross Distribution: What It Includes, and the inherited HSA rules.

Every box in one place: the 1099-SA and 1099-Q boxes table. If your withdrawal came from an IRA or 401(k), see the Form 1099-R Box 7 codes.

Figures verified against the IRS Instructions for Forms 1099-SA and 5498-SA (Rev. December 2026), the IRS Instructions for Form 1099-Q (Rev. April 2025) and the IRS About Form 1099-SA and 1099-Q pages on September 30, 2026.

Sources

Source: the IRS instructions for the filer of each form, read at irs.gov on September 29, 2026. General information, not tax advice. Your own facts decide the outcome, and a preparer, the account provider or the IRS is the right place to confirm anything consequential.