It's written for Australian-based US citizens, green-card holders and expatriates with a Form 1040 obligation. IRS penalties are separate from Australian Taxation Office (ATO) penalties. Paying one doesn't settle the other.
Below: failure to pay versus failure to file, how interest and part-month rules work, what happens after an IRS notice, and which relief options exist.
Key Takeaways
- Filing and paying are separate duties, so a filing extension doesn't extend payment.
- Paying or filing promptly limits further penalty and interest.
- Interest is separate from the penalty and resets quarterly.
- Penalty relief isn't automatic and depends on history and evidence.
What Is the Late Payment Penalty on Form 1040?
The failure-to-pay (FTP) penalty applies to tax left unpaid after the due date. It comes from IRC Section 6651. Section 6651(a)(3) covers extra tax not shown on the return that stays unpaid after notice and demand.
Unpaid tax is the tax required on the return, less withholding, estimated payments and allowable refundable credits. Tax, penalties and interest appear as three different line items on an IRS notice.
A taxpayer may face more than one charge:
- Failure to pay: tax left unpaid after the deadline.
- Failure to file: a missing or late return.
- Underpayment of estimated tax: a separate instalment-based penalty under Section 6654, worked out on Form 2210.
Form 1040 is for individuals. A sole trader reports profit on Schedule C, and partnership or S corporation income flows through to the owner's return, commonly via Schedule E. Those are individual-return charges, not business-return penalties.
Refund position matters as well. If you're owed a refund, the FTP penalty generally does not apply. You should still confirm whether a filing obligation exists. Under Section 6511, a refund claim generally must be made within 3 years of filing or 2 years of payment.
Filing and Payment Deadlines for Form 1040
For most calendar-year individuals, a 2026 return is due 15 April 2027. The 2025 return was due 15 April 2026. A due date falling on a weekend or legal holiday moves to the next business day.
Overseas taxpayers
A US citizen or resident living outside the United States, with their main place of business outside it, generally gets an automatic 2-month extension. For 2025 returns, that moved filing and payment to 15 June 2026.
Interest still runs from 15 April. The late-payment penalty generally doesn't apply if you pay by the extended date, according to IRS Publication 54.
Extensions and special postponements
- Form 4868: a further extension to file, to 15 October 2026 for 2025 returns. It does not extend time to pay.
- Combat-zone service: a postponement applies, with no failure-to-file or failure-to-pay penalties during it.
- Federal disaster relief: governed by the specific IRS disaster notice.
If you expect a balance, send an estimated payment with any extension request. Don't assume Australian residency alone changes your dates.
How the IRS Calculates the Form 1040 Penalty and Interest
| Charge | Rule |
|---|---|
| Failure to pay | 0.5% of unpaid tax per month or part-month, capped at 25% |
| Higher FTP rate | 1% per month after the IRS notice-of-intent-to-levy trigger |
| FTP under installment agreement | 0.25% per month if the return was filed on time |
| Failure to file | 5% per month or part-month, capped at 25% |
| Minimum failure to file (over 60 days late) | Lesser of the fixed minimum or 100% of tax: $510 for 2025 returns, $525 for 2026 |
| Interest (Q4 2026) | 7% annual, compounded daily |
When both penalties apply
The failure-to-file rate is reduced by the FTP amount. During the first five months, the combined charge is 5% per month. Filing on time therefore removes the heavier penalty.
Interest
Interest applies to unpaid tax, penalties and interest, and generally compounds daily. The individual underpayment rate is the federal short-term rate plus 3 points. Rates for 2026 were 7%, 6%, 7% and 7% across the four quarters, per the IRS quarterly rates.
Hypothetical example
Illustrative only, using rates above and simple arithmetic. Interest is simplified.
- Tax unpaid on the due date: US$10,000
- Payment made 2 months and 10 days late (3 months counting part-months)
- FTP penalty: 0.5% × 3 × $10,000 = $150
- Interest at roughly 7% for about 70 days: about $134
- Total to settle: roughly $10,284
The original tax, penalty and interest stay separate on the IRS account.
How to Verify an IRS Penalty Calculation
Compare the notice against your own records:
- The filed Form 1040
- Payment confirmations and withholding records
- Estimated-tax payments and extension records
- Any amended return or IRS adjustment
An IRS Online Account shows balances by year, payment history and notices. Account transcripts confirm assessed amounts and dates.
Online access uses Login.gov or ID.me verification, and mailed transcripts go to the address on your latest return. The IRS can take 4 to 6 weeks to process address changes, so plan ahead if you've moved.
Don't rely only on software estimates or old articles. Minimum penalties and interest rates change.
What Happens After a Form 1040 Payment Is Late?
A few days late is not penalty-free. The IRS charges for a month or part of a month, and interest runs daily. No general grace period applies.
IRS notices
- CP14: first balance-due notice. Pay by the date printed on it.
- CP501 and CP503: reminders, with escalation possible.
- CP504: notice of intent to levy, which can include seizing a state tax refund.
- LT11 / Letter 1058: final notice. Request a Collection Due Process hearing within 30 days.
Check the amount, tax year and deadline against your account. Ignoring notices leads to collection action.
If you can't pay in full
- Pay as much as you can now.
- Short-term plan: generally under $100,000 owed and payment within 180 days, no setup fee.
- Long-term plan: generally $50,000 or less owed with required returns filed. Online direct-debit setup costs $29.
Plan fees are listed on the IRS payment plan page, so confirm them at application. The IRS accepts EFTPS, card and US-dollar international wire for payments sent from outside the US. Your bank may charge fees.
How to Avoid or Reduce the Penalty
Prevention steps
- File a complete, accurate return as soon as possible, even if you can't pay in full.
- Estimate your balance before the deadline.
- Pay by an IRS-approved method and keep the confirmation.
- Check the tax year and taxpayer ID before sending money.
- Review withholding or estimated payments for next year.
Form 4868 avoids the late-filing penalty, but expected tax is still due by the original payment deadline.
Penalty relief options
- First-Time Abatement: needs a clean compliance history, generally the prior 3 years, with returns filed and tax paid or arranged.
- Automatic relief: the IRS announced automatic consideration for eligible returns from tax year 2025, replacing request-based FTA for returns due on or after 1 January 2027.
- Reasonable cause: you must show ordinary business care and prudence. IRS guidance says lack of funds alone generally isn't enough.
- Disaster and IRS error relief: tied to the specific notice or mistake.
The IRS "Fresh Start" initiative is not a blanket waiver.
Requesting relief
Follow the notice instructions. Prepare a factual timeline and supporting documents.
Form 843 is used for abatement of certain penalties and interest, not income tax itself. Use Form 1040-X to change Form 1040 amounts. Approval is never guaranteed.
When Professional Support May Be Useful
Consider a professional review if you have:
- Several unfiled US returns
- Foreign income or investments, including FBAR and Form 8938 reporting
- Treaty or foreign tax credit questions under the US-Australia treaty
- Disputed payments or repeated notices
- A large balance
Streamlined Foreign Offshore Procedures may suit non-willful filers abroad. They aren't a general late-payment waiver.
VJM Global provides Form 1040 support, quoted by entity structure and scope, and has served 250+ Australian businesses. Its team of CPAs, Chartered Accountants and US-compliant professionals can help compile documents and draft responses to IRS notices. Abatement cannot be promised.
Conclusion
Work in this order:
- Confirm the tax year and notice
- Verify the balance
- File any missing return
- Pay what you can
- Pick a payment arrangement
- Check relief eligibility
IRS rules and interest rates are time-sensitive. Use current IRS guidance or qualified cross-border advice before responding to a significant penalty.
Frequently Asked Questions
How much is the IRS penalty for late payment?
It's a percentage of unpaid tax, not a flat fee. The current rate is 0.5% per month or part-month, capped at 25%.
What is the interest rate on penalties for late payments to the IRS?
Interest is separate from the penalty and changes quarterly. For Q4 2026 it's 7% annually, compounded daily. Verify the rate for your dates.
What happens if you pay the IRS a few days late?
The IRS counts a part-month as a full month for the penalty, and interest accrues. Don't assume a grace period.
Will the IRS waive failure to pay penalties?
Possibly, through First-Time Abatement, reasonable cause, disaster relief or correction of an IRS error. Each needs eligibility and evidence.
What happens if I have unpaid taxes?
Penalties and interest keep building, and the IRS sends escalating notices. Payment plans exist, but ignoring notices risks levy.
How do I know if I owe taxes?
Review your Form 1040 balance, payment and withholding records, and IRS notices. Check your IRS Online Account or account transcript for the correct tax year.
