Updated October 17, 2026. Quick answer: Box 8 of Form 1099-OID shows the OID on a U.S. Treasury obligation for the part of the year you owned it. It is kept separate from box 1, and a negative number means a deflation adjustment. The form tells you to report it as interest income on your federal return.
Related reading on this site: IRS Publication 1212.
What box 8 reports
The recipient instructions describe the box this way: “Shows OID on a U.S. Treasury obligation for the part of the year you owned it.” The filer instructions give the matching direction to the payer: “Enter the amount of OID on a U.S. Treasury obligation for the part of the year it was owned by the record holder.”
Box 8 does the same job for Treasury obligations that Form 1099-OID box 1 does for other discounted debt. The two boxes are not meant to overlap: “Do not include this amount in box 1.” The form says the same from your side: “and is not included in box 1.” The rest of the form is laid out in the Form 1099-OID boxes guide.
Where box 8 goes on your return
The form says: “Report this amount as interest income on your federal income tax return and see Pub. 1212 to figure any appropriate adjustments to this amount.”
Publication 550 groups the boxes: “In most cases, you must report the entire amount in Form 1099-OID, boxes 1, 2, and 8 as interest income.” “But see Refiguring OID shown on Form 1099-OID, later in this discussion”. The interest list is on Schedule B (Form 1040), Part I, and the publication notes that “Generally, you report all your taxable interest income on Form 1040 or 1040-SR, line 2b.” The Form 1040 page is Form 1040.
The state and local tax line on the form
The recipient instructions include a sentence about state and local income taxes on this OID. The exact words are: “This OID is exempt from state and local income taxes and is not included in box 1.”
What a negative number in box 8 means
A box 8 figure can be below zero. The form says: “If the number in this box is negative, it represents a deflation adjustment.” “See Pub. 550 for further information on accounting for this adjustment.” The filer instructions give the example: “The amount in box 8 may be a negative number (for example, if a Treasury Inflation Protected Security has a deflation adjustment for the year).”
The publication is where the treatment of the adjustment is explained.
Treasury inflation-protected securities
Publication 550 describes these securities in two places. In the Treasury discussion: “These securities pay interest twice a year at a fixed rate, based on a principal amount adjusted to take into account inflation and deflation.” In the discussion of inflation-indexed debt: “In general, an inflation-indexed debt instrument is a debt instrument on which the payments are adjusted for inflation and deflation” (“such as Treasury Inflation-Protected Securities”).
The reporting consequence: “you must report as OID any increase in the inflation-adjusted principal amount of the instrument that occurs while you held the instrument during the year.” “You should receive Form 1099-OID from the payer showing the amount you must report as OID and any qualified stated interest paid to you during the year.” The qualified stated interest on these securities may show up in box 2, covered on Form 1099-OID box 2, or on a Form 1099-INT; savings bond and other Treasury interest on that form is explained on the Form 1099-INT page on savings bond and Treasury interest.
When the box 8 figure needs refiguring
As with box 1, the printed number is not always the final number. Publication 550 says: “You may need to refigure the OID shown in Form 1099-OID, box 1 or box 8 if either of the following apply.” “You bought the debt instrument after its original issue and paid a premium or an acquisition premium.”
The form points to the acquisition premium box for covered securities: “See the instructions above for a covered security acquired with acquisition premium.” That box is explained on Form 1099-OID box 6. For a covered security with a net figure, “you must report the net amount of OID on Schedule B (Form 1040)”.
Edition and box numbers
Form 1099-OID has one edition on file for this page. The form is marked “(Rev. January 2024)”, and that is the edition the IRS website served as the current form on October 17, 2026. No other edition is compared here, so there is no difference between editions to report. Publication 550 for 2025 returns is used for where amounts go on the return.
Look at the line that reads “For calendar year” on the copy you received and confirm it shows the tax year you are filing before you rely on any box description on this page. The box numbers above are the numbers printed on the form itself.
Common mistakes
- Putting the box 8 amount into the box 1 line as well. The filer instructions say “Do not include this amount in box 1.”
- Treating a negative box 8 as a typo. The form says “If the number in this box is negative, it represents a deflation adjustment.”
- Leaving box 8 off the interest total. The publication says to report “Form 1099-OID, boxes 1, 2, and 8 as interest income.”
Related: savings bond and Treasury interest, Schedule B (Form 1040), Form 1040, and Form 1099-INT box 1.
Sources
- Form 1099-OID (Rev. January 2024) with Instructions for Recipient: https://www.irs.gov/pub/irs-pdf/f1099oid.pdf
- Instructions for Forms 1099-INT and 1099-OID (Rev. January 2024): https://www.irs.gov/pub/irs-pdf/i1099int.pdf
- Publication 550, Investment Income and Expenses (for 2025 returns): https://www.irs.gov/pub/irs-pdf/p550.pdf
Read from the IRS documents linked above on October 17, 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.