Tariffs & HTS
U.S. keeps customs duty interest rates at 7% and 6% for Q4 2026
CBP published the IRS interest rates it uses for overdue customs duties (underpayments) and refunds (overpayments) for October 1 to December 31, 2026. Underpayments carry 7 percent for corporations and non-corporations; overpayments earn 7 percent for non-corporations and 6 percent for corporations, the same rates as the quarter that began July 1, 2026.
What changed
The rates come from IRS Revenue Ruling 2026-15: the federal short-term rate of 4 percent plus three percentage points, or plus two points for corporate overpayments. Under 19 U.S.C. 1505, customs interest follows these Internal Revenue Code rates.
The notice summary says the rates remain the same as the previous quarter, and CBP's July 1 notice (2026-13298) listed the same 7, 7 and 6 percent; one background sentence says the rates 'will increase', but the figures do not change. CBP's historical table now shows a single line for July 1 to December 31, 2026. The rates are subject to change for the quarter beginning January 1, 2027.
What an import team should check
- Ask your broker or finance team to check that bills for underpayment interest use 7 percent, and that refund interest uses 6 percent for corporations or 7 percent for non-corporations.
- Check interest on supplemental duty bills or refunds that span several quarters against CBP's historical rate table rather than one single rate.
- Set a reminder to review CBP's notice for the quarter beginning January 1, 2027, when the notice says these rates are subject to change.