Submitting a late tax return to the IRS (https://www.irs.gov/faqs/irs-procedures/collection-procedural-questions/collection-procedural-questions-3) generally results in a failure-to-file penalty of 5% of the unpaid taxes per month (up to 25%), plus potential interest. If you owe no tax, there are usually no penalties. You should still file to avoid further interest, protect Social Security benefits, or claim a refund.
If you owe tax and don't file on time (with extensions), there's also a penalty for not filing on time. The failure-to-file penalty is usually five percent of the tax owed for each month, or part of a month, that your return is late, up to a maximum of 25%.
Interest will be charged on late payments after this date. If HMRC have asked you to complete a tax return for 2024/25, and you miss the deadline, you'll automatically be fined regardless of how small your tax liability is. A penalty will also apply if you are due a refund.
If you have unpaid taxes and you file your return late, the government charges interest under Section 234A as follows: Interest is charged at 1% per month (or part of a month) on the unpaid tax amount. The interest is calculated from the due date of filing the return until the actual date of filing.
If you file taxes after the October 15 extension deadline, the IRS will assess penalties and interest, primarily a failure-to-file penalty (5% per month, max 25%), plus a separate failure-to-pay penalty (0.5% per month) and daily interest on the unpaid taxes, though you can request penalty abatement for reasonable cause like natural disasters. The October deadline is for filing, not paying; if you owe, payment was due in April, so you'll likely face both penalties and interest until you file and pay, but you won't be penalized if you're due a refund.
You can avoid a penalty by filing and paying your tax by the due date. If you can't do so, you can apply for an extension of time to file or a payment plan.
In addition to a fine, the ATO can also apply General Interest Charges (GIC), on any amount still owing. Note: The rate for GIC changes quarterly. At the time of writing this article, the rate is 10.61% per annum (October – December 2025).
Acceptable reasons include serious illness, natural disasters, or other events beyond your control that prevented timely tax filing or payment. However, ignorance of the law, relying on an advisor, and lack of funds are generally not treated as reasonable causes.
The IRS 3-year rule generally refers to the statute of limitations for claiming a tax refund, which is typically 3 years from when you filed your original return or 2 years from when you paid the tax, whichever is later, for the IRS to process your claim. For an audit, the IRS generally has 3 years from the date your return was filed or due (whichever is later) to assess additional tax, though this can extend to 6 years if you significantly underreport income or omit foreign income.
Don't overlook filing a tax return. There's no penalty for filing after the April 15 deadline if a refund is due. Every year, the IRS estimates nearly a million taxpayers who failed to file prior year tax returns are potentially due refund money.
Examples of valid reasons for failing to file or pay on time may include: Fires, natural disasters or civil disturbances. Inability to get records. Death, serious illness or unavoidable absence of the taxpayer or immediate family.
If you don't file taxes for a year and owe money, you face significant penalties and interest, including a 5% per month failure-to-file penalty (up to 25%), a separate failure-to-pay penalty, and accruing interest, potentially leading to wage garnishment, bank levies, and even criminal charges in extreme cases; however, if you are due a refund, there's no penalty, but you must file within three years to claim it.
One-time forgiveness, officially known as First-Time Penalty Abatement (FTA), is an IRS program that allows qualified taxpayers to have certain penalties removed from their tax accounts.
Sound reasons, if established, include:
Not reporting all of your income is an easy-to-avoid red flag that can lead to an audit. Taking excessive business tax deductions and mixing business and personal expenses can lead to an audit. The IRS mostly audits tax returns of those earning more than $200,000 and corporations with more than $10 million in assets.
Taxpayers usually have three years to file and claim their tax refunds. The three-year deadline for filing 2019 returns to claim a refund was in 2022, but the IRS postponed the deadline to July 17, 2023, due to the COVID-19 pandemic.
If you file taxes after the October 15 extension deadline, the IRS will assess penalties and interest, primarily a failure-to-file penalty (5% per month, max 25%), plus a separate failure-to-pay penalty (0.5% per month) and daily interest on the unpaid taxes, though you can request penalty abatement for reasonable cause like natural disasters. The October deadline is for filing, not paying; if you owe, payment was due in April, so you'll likely face both penalties and interest until you file and pay, but you won't be penalized if you're due a refund.
your partner or another close relative died shortly before the tax return or payment deadline. you had an unexpected stay in hospital that prevented you from dealing with your tax affairs. you had a serious or life-threatening illness. your computer or software failed while you were preparing your online return.
Because this money belongs to you and doesn't accrue interest, filing sooner rather than later to put this money in your pocket makes good financial sense. For most, the best choice is to file taxes early — or at least as soon as you can. This way: The IRS may process your return and agree on your tax liability sooner.
Key takeaways
Owing taxes and filing late can trigger penalties of up to 25% of unpaid tax, plus interest that accrues monthly. Filing past-due returns quickly can reduce penalties, protect Social Security credits, and avoid loan delays.
The biggest tax mistakes people make include filing late, math errors, incorrect personal info (like Social Security numbers), forgetting deductions/credits (like EITC), misreporting income, not signing forms, and making errors with bank details for direct deposit, all leading to delays, penalties, or missed savings, with using tax software or professionals helping avoid these common pitfalls.
If you have a balance owing, the CRA may charge interest and a late-filing penalty on returns filed after the due date. If you file your return after April 30, your GST/HST credit, climate action tax credit, Canada child benefit and B.C. family benefit, and Old Age Security benefit payments may be delayed.