Is IRS refund interest income taxable

Quick answer: No — for 2025, interest the IRS pays you on a refund (an "overpayment") is taxable income to you, even though the underlying tax refund itself isn't taxed.

How it works

When you overpay your federal tax and the IRS refunds it, the IRS is generally required to pay you interest on that overpayment. Under IRC § 6611(b), interest shall be allowed and paid upon any overpayment in respect of any internal revenue tax at the overpayment rate established under section 6621.¹

That interest payment isn't a return of your own money — it's compensation for the IRS holding your money, and it falls squarely within the broad definition of gross income. IRC § 61(a) defines gross income to include "Interest"² as one of the enumerated items of income, and the rule is written expansively: except as otherwise provided in this subtitle, gross income means all income from whatever source derived, including (but not limited to)² the listed categories. Treasury's general regulation on gross income, 26 C.F.R. § 1.61-1, reinforces this: gross income means all income from whatever source derived, unless excluded by law, and gross income includes income realized in any form, whether in money, property, or services.³

Nothing in the documents provided carves out an exclusion for interest paid by the IRS on a refund. Unlike tax-exempt municipal bond interest — which Publication 17 explains is generally excluded when interest on a bond used to finance government operations generally isn't taxable if the bond is issued by a state, the District of Columbia, a territory of the United States, or any of their political subdivisions⁴ — interest from the IRS itself doesn't fit that exclusion category. IRS overpayment interest is ordinary taxable interest income, reportable in the year you receive it.

Reporting

The IRS will typically report interest paid to you on Form 1099-INT, and you report it as interest income on your return, just as you would bank account interest.

In practice

• The tax refund principal itself is not income (it's your own money coming back).
• The interest component on top of that refund is taxable income in the year received.
• If your overpayment relates to a carryback (for example, certain foreign tax credit carrybacks), IRC § 6611(f)(2) has special timing rules for when the "overpayment" is deemed to have been made, which affects how the interest period is calculated, but this doesn't change the fact that the interest itself is taxable once paid.

What it depends on:

The main question in your situation is simply whether the payment you received from the IRS was interest (taxable) versus a refund of tax you already paid (not itself taxable) — check your 1099-INT or the IRS notice describing the payment.

Given how easily refund principal and refund interest get conflated on your return, and because the documents here don't address every edge case (like partial-year Puerto Rico residents or multi-year carrybacks), it's worth a quick check with a CPA if you're unsure how to categorize an IRS payment you received.