Tax season 2026 — extensions and late filing

Extension vs. payment

In every major OECD jurisdiction, an extension of time to file is distinct from an extension of time to pay. Filing for an extension typically avoids the failure-to-file penalty but does not avoid the failure-to-pay penalty or interest on the underpayment.

If you cannot pay the full balance by the original deadline, file the extension anyway and pay as much as you can with the extension. The failure-to-pay penalty (typically 0.5 percent per month in the US) accrues on the unpaid balance but is much smaller than the failure-to-file penalty (5 percent per month).

US automatic extension

Form 4868 grants an automatic 6-month extension to file a personal return. File electronically by the original deadline (15 April 2026 for the 2025 tax year). No reason or justification required.

If you e-file Form 4868 electronically, the IRS confirms receipt within hours. Paper filing of Form 4868 is permitted but slower; retain the certified-mail receipt as proof of timely filing.

Some state returns require a separate state extension request; many states automatically grant the federal extension if Form 4868 was filed timely. Check the specific state's rules at the state tax authority's website.

UK late filing

HMRC penalties for late filing of Self-Assessment returns:

• 31 January deadline missed: GBP 100 immediate penalty regardless of whether tax is owed.
• 3 months late (1 May): daily penalties of GBP 10 per day for 90 days, capped at GBP 900.
• 6 months late (1 August): additional 5 percent of tax owed or GBP 300, whichever higher.
• 12 months late (1 February next year): additional 5 percent of tax owed or GBP 300, whichever higher; deliberate concealment can increase this materially.

Reasonable-excuse appeals are accepted by HMRC for genuine emergency situations (serious illness, bereavement, natural disaster); routine forgetfulness or workload pressure does not qualify. Submit appeal within 30 days of the penalty notice.

Canada late filing

CRA penalties: 5 percent of balance owing immediately, plus 1 percent per month up to 12 months. Repeated late filing (within 3-year window) doubles the penalty rate to 10 percent immediate plus 2 percent per month.

Self-employed individuals' filing deadline is 15 June 2026 but tax payment is still due 30 April 2026; interest accrues on any unpaid balance from 1 May 2026 even though the filing deadline hasn't been reached.

Australia late filing

ATO failure-to-lodge penalty: 1 penalty unit per 28-day period, up to 5 penalty units for individuals (penalty unit value AUD 313 for 2024-25, indexed). Penalties may be remitted on application where reasonable excuse applies.

Engaging a registered tax agent under the lodgement program provides automatic extensions to varying dates through the year following the tax year-end; check with the agent for the specific date applicable.

Tax-payment plans

Most major OECD tax authorities offer payment-plan options for filers who cannot pay the balance owed in full at filing time:

• US (IRS): short-term payment plan (up to 180 days) or long-term installment agreement (over 180 days). Apply via Form 9465 or via the IRS online installment agreement tool. Setup fees apply for installment agreements; long-term plans require direct-debit setup for fees to be reduced.
• UK (HMRC): Time to Pay arrangement available via the HMRC online portal or by calling HMRC. Typically up to 12 months for individual self-assessment.
• Canada (CRA): payment arrangement available via My Account or CRA call line.
• Australia (ATO): payment plan available via ATO online services or registered tax agent.

Payment plans avoid further enforcement (levies, garnishments, asset liens) as long as the plan is being honoured. Defaulting on a payment plan typically results in the full balance becoming immediately enforceable.

Filing late without an extension

If you have missed the original deadline and didn't file an extension, file as soon as possible regardless. The failure-to-file penalty stops accruing once the return is filed; the longer you wait, the larger the penalty grows.

Even if you cannot pay the balance owed, file the return. Filing with a balance owed and no payment is materially better than not filing at all; the failure-to-pay penalty is much smaller than the failure-to-file penalty.

Reasonable-cause penalty abatement (US)

The IRS may abate failure-to-file and failure-to-pay penalties for reasonable cause. Reasonable cause typically requires: a specific circumstance beyond the filer's control (serious illness, family death, natural disaster affecting the filer's records, IRS error in prior-year processing); a demonstration that the filer exercised ordinary business care and prudence; reasonable timing of the response once the cause was resolved.

First-time-abate (FTA) administrative waiver is available if you have not received an FTA waiver in the prior 3 years and have filed required returns and paid required tax for the past 3 years. FTA is a streamlined waiver that doesn't require demonstrating reasonable cause.

When to engage a tax pro for late-filing situations

Late-filing situations involving multiple years of unfiled returns, foreign-asset reporting non-compliance, or potential criminal exposure (deliberate non-filing, large unreported income) should not be DIY. Engage a tax professional with controversy experience. Voluntary disclosure programs (US Streamlined Filing Procedures, US OVDP-equivalent for FBAR violations, UK Worldwide Disclosure Facility, Canada Voluntary Disclosure Program) typically offer penalty mitigation if approached before the tax authority initiates contact.

The streamlined-filing-procedures topic hub covers the US-specific framework; equivalent jurisdiction-specific topic hubs cover the UK, Canada, Germany, and Italy frameworks.