This is a planning estimate for ordinary individual federal income tax returns, tax years 2022–2026. It uses the ordinary IRS deadlines: April 18 and October 16, 2023 for 2022 returns, and April 15 and October 15 of the following year for 2023–2026 returns. Disaster, overseas and combat-zone adjustments, and the April 17, 2024 deadline for Maine and Massachusetts filers, are not included.
Not included: estimated-tax underpayment penalties (Form 2210), state taxes, business-return penalties, fraud or accuracy penalties, amended-return assessments, installment-agreement rate reductions, levy rate increases, bankruptcy, and interest on assessed late-payment penalties. Payments you enter are applied to tax only. Actual IRS payment allocation and rounding may differ.
The late-filing penalty uses the tax unpaid at the original April deadline, even if it was paid later. After 60 days the minimum is the smaller of that unpaid tax or $450 for returns due in 2023, $485 in 2024, $510 in 2025, $525 in 2026 and $535 in 2027. The minimum can exceed the usual percentage cap.
Penalty relief may be available depending on your circumstances. No first-time abatement or reasonable-cause relief is assumed, apart from the optional extension payment exception. IRS: penalty relief ↗
More sources: IRS penalty manual (IRM 20.1.2) · IRS interest rules. The rates are a reviewed snapshot, not a live feed. Confirm current rules before relying on an estimate.