Quarterly rates
Uses the IRS standard underpayment rate for every day in the selected period, from 2017 through Q3 2026.
IRS Interest Calculator
Methodology Not affiliated with the Internal Revenue Service, Department of the Treasury, or the United States Government.
Federal tax underpayment interest
Interest estimated,
quarter by quarter.
Today's underpayment rate
7.00%Standard rate · Q3 2026Estimate interest across IRS rate changes with daily compounding, including the enhanced rate used for BBA push-out adjustments.
02 / Estimate
Standard underpayment rateEstimated interest
$14,736.16
Estimated total due $39,736.16- Interest days
- 3,014
- Effective cost
- 58.94%
- Avg. annual rate
- 5.62%
Rate-by-rate calculation
12 periods| Period | Days | Rate | Interest |
|---|---|---|---|
| Apr 16, 2018 – Dec 31, 2018 | 260 | 5.00% | $906.39 |
| Jan 1, 2019 – Jun 30, 2019 | 181 | 6.00% | $782.32 |
| Jul 1, 2019 – Jun 30, 2020 | 366 | 5.00% | $1,370.20 |
| Jul 1, 2020 – Mar 31, 2022 | 639 | 3.00% | $1,511.77 |
| Apr 1, 2022 – Jun 30, 2022 | 91 | 4.00% | $296.36 |
| Jul 1, 2022 – Sep 30, 2022 | 92 | 5.00% | $378.76 |
| Oct 1, 2022 – Dec 31, 2022 | 92 | 6.00% | $460.85 |
| Jan 1, 2023 – Sep 30, 2023 | 273 | 7.00% | $1,650.35 |
| Oct 1, 2023 – Dec 31, 2024 | 458 | 8.00% | $3,408.50 |
| Jan 1, 2025 – Mar 31, 2026 | 455 | 7.00% | $3,260.80 |
| Apr 1, 2026 – Jun 30, 2026 | 91 | 6.00% | $588.13 |
| Jul 1, 2026 – Jul 16, 2026 | 16 | 7.00% | $121.73 |
Methodology
Built around published IRS rules.
Daily compounding
Accrues interest at the annual rate divided by 365, or 366 in a leap year, and adds it to the balance each day.
Enhanced rate
BBA push-out and applicable large-corporate periods substitute 5 percentage points for the standard 3-point spread.
COVID court scenario
The nationwide emergency was declared Mar. 13, 2020, with a FEMA incident period beginning Jan. 20. This option applies the Kwong interpretation through July 10, 2023; the law remains unsettled.
Planning estimate only. The COVID exclusion is a disputed court-based scenario, not settled IRS treatment. Otherwise, this calculator does not include penalties, payments during the period, other interest suspensions, abatements, netting, or case-specific adjustments. Verify against IRS records and qualified advice.