The Internal Revenue Service (IRS) has announced that interest rates will increase for the third quarter of 2026, beginning July 1. These rates, which remain in effect through September 30, 2026, impact taxpayers with outstanding tax balances as well as those eligible to receive interest on delayed refunds. Understanding the latest IRS interest rates can help individuals and businesses make informed financial decisions and minimize unnecessary interest costs.
Understanding the IRS Q3 2026 Interest Rates
For the third quarter of 2026, the IRS has increased interest rates across all categories by one percentage point compared to Q2. The adjustment reflects an increase in the federal short-term rate, which the IRS uses to calculate quarterly interest rates. Whether you owe taxes or expect interest on a delayed refund, these updated rates could affect your overall tax situation.
Rates for Individual Taxpayers
Individual taxpayers will pay 7% interest on underpayments and receive 7% interest on qualifying overpayments, with interest compounded daily. This is up from 6% during the second quarter of 2026.
The higher rate means unpaid tax balances will grow more quickly if left unresolved. While taxpayers receiving interest on delayed refunds will benefit from the increased rate, most refunds issued within the IRS’s standard processing timeframe do not qualify for interest. The IRS only starts paying interest on a refund if it takes longer than 45 days to arrive. If your refund shows up within that window, you won’t see any interest at all — delayed or not.
Rates for Corporate Taxpayers
Corporate taxpayers will encounter the following interest rate structure in Q3 2026:
- Overpayments: 6% per year, compounded daily
- Portion of Overpayment Over $10,000: 4.5% per year, compounded daily
- Underpayments: 7% per year, compounded daily
- Large Corporate Underpayments (LCU): 9% per year, compounded daily
Each of these rates represents a 1% increase from the previous quarter, reflecting the IRS’s quarterly adjustment based on prevailing economic conditions.
How the IRS Determines These Rates
The IRS calculates interest rates every quarter using the federal short-term rate established by the U.S. Treasury, with fixed percentages added based on the type of taxpayer and transaction.
For most individual taxpayers, both overpayment and underpayment rates equal the federal short-term rate plus 3 percentage points.
Corporate taxpayers follow a different formula. Corporate underpayments are calculated using the federal short-term rate plus 3 percentage points, while corporate overpayments use the short-term rate plus 2 percentage points. Large corporate underpayments are assessed at the federal short-term rate plus 5 percentage points, and the portion of a corporate overpayment exceeding $10,000 earns interest at just 0.5 percentage points above the federal short-term rate.
Although the formulas remain the same from quarter to quarter, the resulting rates rise or fall as the federal short-term rate changes.
Financial Implications of the Q3 Rate Increase
While a one-percentage-point increase may seem modest, it can significantly impact taxpayers who carry unpaid balances for several months. Because IRS interest compounds daily, even small increases can noticeably raise the total amount owed over time.
Taxpayers who owe the IRS should expect balances to grow faster than they did during the second quarter. On the other hand, taxpayers whose refunds qualify for IRS interest will receive a slightly higher return. Businesses with significant tax liabilities or large overpayments should also consider how the higher rates affect cash flow and financial planning.
Strategic Considerations for Taxpayers
With interest rates increasing, resolving tax issues promptly becomes even more important. Paying outstanding balances as soon as possible—even if only through partial payments—can reduce the amount of interest that accrues over time.
Taxpayers should also continue filing returns on time, even if they cannot pay the full balance owed. Filing timely can help avoid additional penalties, while setting up an installment agreement may provide a manageable way to pay outstanding taxes, although interest will generally continue to accrue until the balance is paid in full.
Businesses should review their payment strategies and estimated tax obligations to avoid unnecessary interest charges during the higher-rate quarter.
Tax Help in 2026
As IRS interest rates rise, now is a good time to evaluate your tax situation with a qualified tax professional. Whether you have an outstanding balance, need assistance establishing a payment plan, or want to explore options for reducing penalties, professional guidance can help you minimize the long-term cost of unresolved tax debt. Taking action sooner rather than later can help prevent interest from continuing to compound and increase the amount you ultimately owe. Optima Tax Relief is the nation’s leading tax resolution firm with over $3 billion in resolved tax liabilities.
If You Need Tax Help, Contact Us Today for a Free Consultation.