IRS Interest Rates for Late Taxes 2026: Rates, Daily Compounding, and Examples

For most individual late tax balances, the IRS interest rate is the ordinary underpayment rate. In 2026, the IRS listed that rate as 7% for Q1 2026 and 6% for Q2 2026. The IRS had not yet listed Q3 or Q4 2026 rates on its quarterly interest rate page when this guide was updated on May 14, 2026.

Interest is separate from IRS penalties. The IRS says it charges interest on unpaid tax, penalties, additions to tax, and interest until the balance is paid in full. The interest rate can change by calendar quarter and is compounded daily.

The IRS publishes quarterly interest rates for underpayments and overpayments. For late tax balances, the key number for most people is the underpayment rate. Corporate balances can have different overpayment and large corporate underpayment rates.

The official IRS quarterly table also lists the portion of a corporate overpayment exceeding $10,000: 4.5% for Q1 2026 and 3.5% for Q2 2026. That category usually does not matter for an individual late Form 1040 balance, but it matters in corporate tax accounting.

IRS interest is not a one-time fee. It is a finance charge on the unpaid account balance. The rate is set quarterly under the tax code, and the IRS compounds the charge daily. When the rate changes at the start of a new quarter, the unpaid balance can be subject to the old rate for earlier days and the new rate for later days.

For a fast planning estimate, many taxpayers multiply the balance by the annual rate and prorate by days unpaid. That is useful for scale, but the IRS notice can differ because it uses daily compounding, actual account dates, payments, credits, penalties, and any rate changes across quarters.

IRS interest and IRS penalties are related but not the same. Interest is the time-value charge. Penalties are separate charges for behavior such as filing late, paying late, or underpaying estimated tax.

This distinction matters because penalty relief does not automatically wipe out all interest. If the IRS removes a penalty, interest that accrued on that penalty can also be reduced. Interest on tax that was actually unpaid usually remains.

For unpaid income tax, interest generally starts after the original payment due date. A filing extension can protect you from the failure-to-file penalty if used correctly, but it generally does not extend the deadline to pay.

That is why an April balance can accrue interest even when the return itself is filed by the October extension deadline. The unpaid tax was still due by the original payment deadline.

These examples use simple prorated estimates so the math is easy to follow. The exact IRS number can differ because IRS interest compounds daily, payments can arrive on different dates, penalties can be added, and the rate can change by quarter.

The examples also exclude the failure-to-pay penalty. For example, a $10,000 balance that is 60 days late in Q2 2026 may have roughly $98.63 of simple interest estimate, but the late-payment penalty can add a separate monthly amount.

No. An IRS payment plan can make the balance easier to manage and may lower the monthly failure-to-pay penalty for eligible individuals, but interest generally continues until the balance is fully paid.

A payment plan can still be valuable because it can organize collections, reduce default risk, and prevent the balance from being ignored. It does not turn a tax balance into a no-interest loan.

Estimated tax penalties use an interest-rate style calculation. IRS revenue rulings state that the underpayment rate under section 6621 applies when determining additions to tax for underpayment of estimated tax by individuals and corporations.

For 2026 planning, that means the quarterly underpayment rates matter not only after a return shows a balance due, but also when a taxpayer did not pay enough through withholding or estimated payments during the year.

If your income was uneven, the annualized income method may matter. That is especially common for self-employed taxpayers, investors, seasonal earners, and people with a large bonus, capital gain, or business distribution.

IRS interest can also work in the taxpayer's favor. When the IRS owes interest on an overpayment or delayed refund, the overpayment rate category can apply. The IRS quarterly table lists non-corporate overpayment rates of 7% for Q1 2026 and 6% for Q2 2026.

Refund interest rules have their own timing requirements, and not every delayed refund earns interest. The main point for this late-tax guide is that underpayment and overpayment rates are published together, but they apply to different account situations.

Most small businesses organized as sole proprietorships, single-member LLCs, partnerships, or S corporations ultimately affect an owner's individual tax balance. But corporate taxpayers can face separate corporate rate categories.

Payroll tax deposits, trust fund recovery issues, and employment tax penalties can create additional business-specific exposure. Use this guide for the interest-rate layer, then separately review the penalty rules for the tax type involved.

IRS interest is usually mechanical. The best strategy depends on whether the underlying balance is correct.

If the balance is correct, paying sooner is the most reliable way to reduce future interest. If the balance is not correct, fix the account record. A removed tax assessment, corrected payment credit, or abated penalty can also remove interest tied to that amount.

CalculatorWallah tools can estimate the tax side of the problem before you deal with the IRS account mechanics. They do not replace an IRS transcript or notice, but they help you understand why the balance exists.

The IRS has a short official video that fits this topic well. It explains why filing and paying on time matter, why extensions do not extend the payment deadline, and why paying as much as possible can help reduce penalties and interest.

For the official current table, check the IRS quarterly interest rates page. For account-specific amounts, use the actual IRS notice, payment records, and tax transcript.

Read the companion guides when your balance includes penalties, missed deadlines, or estimated tax issues in addition to interest.