Compliance
Understanding Interest Rates, Underpayments, and Overpayments: What’s Changing in Q2 2026
The IRS has set new interest rates for Q2 2026 affecting underpayments, overpayments, and corporate vs individual obligations—important for cash-flow planning and compliance.
By NomadicTax Research Team • 5-8 min read • April 22, 2026
## New IRS Interest Rates for April-June 2026
The IRS updated interest rates for the second quarter of 2026 (April-June) across several categories such as underpayments, overpayments, corporate vs non-corporate entities. These affect penalty assessments, refunds, and accruals. ([irs.gov](https://www.irs.gov/payments/quarterly-interest-rates?utm_source=openai))
Here are the primary rates:
| Category | Q2 2026 Rate |
|----------|-----------------------------|
| Overpayment (non-corporate) | 6% |
| Overpayment (corporate) | 5% |
| Underpayment (corporate & non-corporate) | 6% |
| GATT overpayment (> $10,000 corporate overpayment) | 3.5% |
| Large corporate underpayment (LCU) | 8% |
| Federal short-term rate (IRC 6603 deposits) | 3% |
## Who This Affects Most
- **Individuals and small businesses** that owe estimated taxes—higher underpayment rate means late payments carry steeper interest.
- **Corporations** with overpayment balances—earning slightly lower rate.
- **Corporate filers with large amounts owed**: “large corporate underpayment” saw rate remain steep.
- **Refund-seeking taxpayers**: Overpayments will accrue interest, but at lower rates for corporate or GATT categories.
## Practical Tips & Examples
- If you expect to owe taxes and haven’t paid enough via withholding or estimated payments, consider making a payment before Q2 ends to reduce underpayment interest.
- Overpayments held by the IRS earn 6% (non-corporate), so filing sooner can start the clock on interest sooner.
- Corporate entities should assess whether to prepay certain liabilities or adjust deposits to avoid falling into large underpayment penalties.
**Example**: An individual self-employed with $10,000 estimated tax due, paid late by 30 days, might pay approximately **(principal × rate × days/365)** = $10,000 × 6% × 30/365 ≈ **$49 interest**. For a corporation with similar late payment in LCU category, rate would be 8%, so interest higher.
## Action Plan for 2026 Q2
- Review your estimated tax payments schedule; adjust if needed.
- Track your overpayment/underpayment status and possible refund timings.
- For businesses, integrate interest rate changes into cash-flow planning for liabilities.
## Bottom Line
This rate change may seem technical, but it impacts penalties, refunds, and timing. **Staying ahead can save money and reduce surprises**.