Updated September 30, 2026. Quick answer: Box 4 of Form 1099-INT is backup withholding. Box 5 is investment expenses for a narrow kind of payer. Box 6 is foreign tax paid on the interest and Box 7 names the country.
Foreign tax credit (Form 1116) and alternative minimum tax (Form 6251) for 2025, read line by line: Form 1116 line 8, Form 1116 lines 9 to 14 and Form 1116 lines 25 to 32.
Schedule A and Schedule B (Form 1040) for 2025, read line by line: Schedule A lines 6 and 7 and Schedule B line 7.
Schedule 3 (Form 1040) for 2025, read line by line: Schedule 3 line 1.
Read box by box from the IRS form text: Form 1099-OID boxes explained, Form 1099-OID box 2 and Form 1099-OID box 8.
Related reading on this site: FBAR deadline 2027.
The recipient copy of Form 1099-G or 1099-K, read box by box: 1099-G boxes 2 and 3 and 1099-K box 4 and boxes 5a to 5l.
More IRS forms and schedules, read line by line: Form 1042-S instructions.
More IRS forms and schedules, read line by line: Form W-9 instructions.
More IRS forms and schedules, read line by line: Form 5471 instructions and Form 8833 instructions.
The IRS form or worksheet behind this, read line by line: Schedule B instructions and Form 8621 instructions.
The IRS form or worksheet behind this, read line by line: Form 1116 and the foreign tax credit.
Box 4: federal income tax withheld
The instruction is “Enter backup withholding.” For example: “if a recipient does not furnish its TIN to you in the manner required, you must backup withhold on payments required to be reported in box 1 (which may be reduced by the amount reported in box 2), box 3, and box 8 on this form.” The 1099-INT instructions read here are the January 2024 revision (combined with Form 1099-OID), which is the edition irs.gov shows as current for those forms. Those are instructions to the payer that files the form, so they show what a box is meant to hold, not what tax follows from it. The rate is not stated in these instructions.
Box 5: investment expenses
Box 5 is for a narrow case. The instruction says “For single-class REMICs only” and adds “Note. This amount is not deductible.”
Boxes 6 and 7: foreign tax
Box 6 reads “Enter any foreign tax paid on interest. Report this amount in U.S. dollars.” Box 7 is “Enter the name of the foreign country or U.S. territory for which the foreign tax was paid and reported in box 6.”
Where the interest boxes are
The interest itself is in Box 1, Box 3 and Box 8.
Common mistakes
- Reading Box 4 as a refund due. It is tax the payer held back.
- Expecting Box 5 on a bank statement. It applies to single-class REMICs.
- Looking for a state amount here. The state boxes are 15 to 17.
Related: 1099-INT Box 1 Interest Income: What Counts, and 1099-DIV Box 4 Withholding and Box 7 Foreign Tax Paid.
Every box in one place: the 1099-DIV, 1099-INT and 1099-B boxes table. If your withdrawal came from an IRA or 401(k), see the Form 1099-R Box 7 codes.
Sources
- IRS, Instructions for Form 1099-DIV (Rev. January 2024): irs.gov/pub/irs-pdf/i1099div.pdf
- IRS, Instructions for Forms 1099-INT and 1099-OID (Rev. January 2024): irs.gov/pub/irs-pdf/i1099int.pdf
- IRS, Instructions for Form 1099-B (2026): irs.gov/instructions/i1099b
Source: the IRS instructions for the filer of each form, read at irs.gov on September 30, 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.