Taxpayers who owe the IRS money and have not paid in full will keep facing a 7% annual interest rate for the fourth quarter of 2026, the agency announced, meaning any balance carried past the October filing deadline keeps compounding at the same rate that has applied for months. The rate, calculated separately from any late-payment penalty, holds for the quarter beginning Oct. 1 and accrues daily until the balance is paid off. For anyone who requested a filing extension in April and still owes tax, the announcement confirms that waiting has not gotten any cheaper.
How the Quarterly Rate Is Set
Under the Internal Revenue Code, the IRS recalculates its interest rate every quarter based on the federal short-term rate, adding three percentage points for individual underpayments and overpayments. In IR-2026-98, the agency confirmed the rate computed from July 2026’s federal short-term rate keeps the individual underpayment and overpayment rate at 7% for the quarter beginning Oct. 1, 2026, matching the rate that applied for the prior quarter.
The structure differs for businesses. Corporations that overpay their taxes earn a smaller 6% rate, while large corporate underpayments carry a steeper 9% rate, a premium meant to discourage bigger companies from treating an unpaid tax bill like an interest-free loan. The formal rate table is published each quarter in a Revenue Ruling — Revenue Ruling 2026-15 for this cycle — which also sets the rate on the portion of a corporate overpayment above $10,000 at a lower 4.5%.
Individuals who overpay their taxes earn the same 7% back if the IRS owes them a refund that takes longer than 45 days to issue after the filing deadline, so the rate cuts both ways depending on which side of the ledger a taxpayer is on.
The rate has moved considerably over the past two decades, and the historical table published alongside Revenue Ruling 2026-15 shows just how far. The individual rate sat at a rock-bottom 3% for most of 2011 through 2015 and again touched 3% in 2020 as the Federal Reserve cut rates during the pandemic, before climbing steadily as the Fed raised rates, reaching an 8% peak for every quarter of 2023 and 2024. It has held between 6% and 7% through 2026, dipping to 6% for the second quarter before returning to 7% for the third quarter and now the fourth, underscoring that even a rate the IRS calls unchanged can still move within the same year.
Free retirement updates: Enrollment and claim windows come and go, and missing one can cost you real money. The free Retirement Shield newsletter keeps you ahead of the deadlines that matter. Sign up free.
Why October Matters for Late Filers
Interest accrues daily starting from the original April filing deadline, not from October, so anyone who requested the standard six-month extension and still owes money has already been accumulating interest since spring even though the return itself is not due until mid-October. The Oct. 1 date marks the start of the next quarterly interest-rate period, not the creation of a new liability.
Interest is separate from, and stacks on top of, the failure-to-pay penalty, which the IRS generally assesses at 0.5% of the unpaid balance per month, up to a cap of 25% of the total owed. Someone who owes several thousand dollars past the deadline can watch the combined interest and penalty add up to real money within a matter of months, even before the IRS takes any collection action.
Because both charges compound, a balance that looked manageable in April can grow noticeably larger by the time a taxpayer finally addresses it in the fall, particularly if the underlying amount involves several thousand dollars tied to a large one-time income event.
Taxpayers who are disputing part of a bill but want to stop interest from piling up while the dispute is resolved have a lesser-known option: a Section 6603 deposit, which locks in a lower 4% rate for the fourth quarter rather than the 7% underpayment rate, and can be refunded with interest if the disputed amount is ultimately reduced. The same 7% underpayment rate set in Revenue Ruling 2026-15 also governs the penalty for underpaying estimated taxes during the quarter, a detail that matters for retirees who make quarterly payments on required minimum distributions, pension income or investment gains rather than having tax withheld from a paycheck.
Why a Fixed Income Makes the Rate Riskier
A 7% compounding rate is higher than what most savings accounts or certificates of deposit currently pay, which means letting an IRS balance sit unpaid is effectively a worse deal than borrowing from almost any other common source, including many credit cards during an introductory period. Retirees living on Social Security and modest savings who fall behind on a tax bill — often after an unexpected withdrawal from a retirement account pushed their taxable income higher than usual — face the same 7% clock as anyone else, with no reduced rate tied to age or income level.
A required minimum distribution, an inherited IRA withdrawal, or a lump-sum pension payout can all push someone into owing more than they withheld during the year, and the resulting balance starts accruing interest from the April deadline regardless of when the extra income arrived.
The IRS offers payment plans, including short-term arrangements of up to 180 days and longer installment agreements, that stop collection enforcement but do not stop interest from accruing on the remaining balance. Taxpayers who cannot pay in full by October are generally better off filing, paying what they can on time, and arranging a payment plan for the rest, rather than letting the balance sit unaddressed while it compounds at nearly double what many savers currently earn on cash.
The IRS reviews the rate every quarter, so the 7% figure locked in for the final months of 2026 is not guaranteed to hold into 2027. For now, it gives taxpayers with an outstanding balance a firm number to weigh against a payment plan, a retirement-account withdrawal timed to cover the bill, or other options before the amount owed grows any larger.
This article was researched and drafted with the assistance of artificial intelligence.
More Financial Reading
