On Form 1099-SA, the federal ID number sits in the upper-left corner of the form under the label “PAYER’S TIN.” It appears directly below the trustee or payer’s name and address block, next to the “RECIPIENT’S TIN” field that holds your own Social Security number. It is not in any numbered box. The form only has Boxes 1 through 5, so if a guide points you to a “Box 10,” that box does not exist on this form.1Internal Revenue Service. Form 1099-SA – Distributions From an HSA, Archer MSA, or Medicare Advantage MSA
The number is nine digits, formatted XX-XXXXXXX. TIN stands for Taxpayer Identification Number, and for a financial institution it is the same as its Employer Identification Number (EIN). Copy B, the one you keep for filing, uses the same layout as the other copies, so the TIN is always in that upper-left quadrant, clearly separated from the numbered boxes below.
Whose Number This Actually Is
The “payer” is the trustee or custodian of your HSA, Archer MSA, or Medicare Advantage MSA. That is usually a bank, credit union, insurance company, or brokerage firm that administers the account and processes distributions.1Internal Revenue Service. Form 1099-SA – Distributions From an HSA, Archer MSA, or Medicare Advantage MSA
The TIN does not belong to you, to your employer, or to the medical provider who received payment from the account. It belongs to the financial institution alone. The IRS uses it to match the distribution your custodian reported against what you enter on your return. When the two don’t line up, you hear about it.
Why It Isn’t in a Numbered Box
Form 1099-SA has two sections. The top section holds identifying information about the payer and the recipient. The bottom section holds the five numbered boxes reporting the money side of things. The payer’s TIN is identifying information, so it lives up top.
Here is what actually sits in each of those five numbered boxes, so you can rule them out at a glance:
- Box 1: gross distribution amount for the year.
- Box 2: earnings on excess contributions withdrawn by the filing deadline.
- Box 3: a distribution code identifying the type of withdrawal.
- Box 4: fair market value of the account on the date of death, if applicable.
- Box 5: the type of account (HSA, Archer MSA, or Medicare Advantage MSA).
None of those carry the payer’s ID number.1Internal Revenue Service. Form 1099-SA – Distributions From an HSA, Archer MSA, or Medicare Advantage MSA
Form 5498-SA, the companion form that reports contributions rather than distributions, places the payer’s TIN in the same upper-left position, so the location guidance here works for that form too.2Internal Revenue Service. Instructions for Forms 1099-SA and 5498-SA
If the TIN Is Missing, Wrong, or the Form Hasn’t Arrived
Your custodian is generally required to send Form 1099-SA by January 31 following the tax year of the distribution. If January 31 lands on a weekend, the deadline moves to the next business day.
If the payer’s TIN field is blank, illegible, doesn’t follow the XX-XXXXXXX format, or shows fewer than nine digits, contact your HSA or MSA custodian and ask for a corrected form. A corrected Form 1099-SA will have the “CORRECTED” box checked at the top.1Internal Revenue Service. Form 1099-SA – Distributions From an HSA, Archer MSA, or Medicare Advantage MSA
Wait for the corrected form before filing. The IRS matches your entries against what your custodian submitted electronically, and a mismatched TIN can trigger a notice or hold up your refund. If April is closing in and the corrected form still hasn’t arrived, filing Form 4868 for an extension buys you time, provided you pay any estimated tax owed by the original due date.
One shortcut before you call: many custodians post 1099-SA documents to your online account portal well before the paper copy shows up in the mail. Check there first.