Statutory interest

The interest rate CBP is legally required to pay on refunded duties under 26 U.S.C. § 6621 — currently around 6% annually, floating with the federal short-term rate plus 2%. Accrues from the date the duty was paid until the refund is disbursed. On the ~$166B IEEPA balance, that works out to roughly $650M per month ($21.4M per day) that the Treasury owes importers for every day refunds sit in the queue.