Tax season 2026 — filing deadlines overview

Major-jurisdiction filing deadlines for the 2025 tax year

This article summarises the filing deadlines that apply for the 2025 tax year (returns due in 2026) across the directory's top-30 jurisdictions. Cross-reference with the relevant country deep page for jurisdiction-specific detail.

United States: Form 1040 due 15 April 2026 (Wednesday); automatic 6-month extension to 15 October 2026 via Form 4868. FBAR (FinCEN 114) due 15 April 2026 with automatic extension to 15 October 2026. Form 8938 follows the 1040 filing deadline.

United Kingdom: Self-Assessment tax-year-end 5 April 2026. Paper return due 31 October 2026; online return due 31 January 2027 (also payment deadline for the 2025-26 tax year). HMRC Making Tax Digital for ITSA mandatory for landlords and self-employed individuals with income above GBP 50,000 from 6 April 2026.

Canada: T1 individual return due 30 April 2026 for most filers; self-employed individuals' return due 15 June 2026 with payment due 30 April 2026. Quebec residents file separate provincial return TP-1.

Australia: Individual return due 31 October 2026 for self-prepared filers; with registered tax-agent representation, extension to varying dates through 15 May 2027 depending on agent's lodgement program.

Germany: Steuererklärung due 31 July 2026 for self-prepared filers; with Steuerberater representation, extension to last day of February 2028 (Verlängerung). Filing electronically via ELSTER.

France: Déclaration de revenus due late May to early June 2026 (department-by-department schedule under DGFiP). Online filing mandatory for most filers.

Other major jurisdictions: see country-specific deep pages for the detailed schedule.

Quarterly estimated tax deadlines (US-specific)

For US filers required to make quarterly estimated tax payments under IRC §6654:

Q1 2026 estimated tax: 15 April 2026.
Q2 2026 estimated tax: 15 June 2026 (note: Q2 deadline falls earlier than calendar-quarter-end due to the irregular IRS schedule).
Q3 2026 estimated tax: 15 September 2026.
Q4 2026 estimated tax: 15 January 2027.

Safe-harbour rules to avoid underpayment penalty: pay 100 percent of prior-year tax (110 percent for AGI above USD 150,000) or 90 percent of current-year tax. The quarterly-estimated-tax topic hub covers the framework in detail.

Cross-jurisdiction coordination

If you have filing obligations in multiple jurisdictions (US-citizen-abroad, expat returns), coordinate the deadlines: many jurisdictions' deadlines overlap with the US 15 April / 15 October cycle, but some (UK 31 January; AU 31 October self-prep) fall outside the US window.

Treaty-position elections and foreign-tax-credit calculations often require both jurisdictions' returns to be partially complete before either can be finalised. Build the schedule with this dependency in mind.

Penalty exposure

Late filing without extension typically generates: (a) failure-to-file penalty as a percentage of unpaid tax (US: 5 percent per month up to 25 percent; UK: GBP 100 immediate plus daily penalties after 3 months; Canada: 5 percent of balance owing plus 1 percent per month up to 12 months); (b) failure-to-pay penalty (US: 0.5 percent per month up to 25 percent; UK: 5 percent at 30 days, 6 months, and 12 months); (c) interest accrual on the underpayment.

Filing for extension is free in most jurisdictions and avoids the failure-to-file penalty even if you cannot pay the full balance by the original deadline; the failure-to-pay penalty still accrues but at a smaller rate than failure-to-file.

Engagement with tax professionals

Engagement letters typically need to be in place 30-60 days before the filing deadline to allow time for document gathering and return preparation. Last-minute engagements (within 14 days of deadline) are not always accepted by firms operating at capacity; expect rush fees or referral to another firm.

The directory's firm profiles list typical engagement-window expectations and peak-season capacity policy.