Q1 — January through March
Jan 15
Q4 2025 estimated tax payment dueFinal installment of 2025 estimated taxes (Form 1040-ES). Applies to self-employed, freelancers, and anyone with significant non-W-2 income.
Jan 26
IRS begins accepting 2025 tax returnsThe IRS officially opens its systems to receive and process 2025 individual returns.
Feb 2
W-2s and 1099s must be in your handsEmployers and payers are required to have your W-2 and 1099-NEC forms delivered by this date (Jan 31 falls on a Saturday in 2026).
Feb 17
W-4 withholding exemption renewalIf you claimed exempt from withholding on your 2025 W-4, you must file a new W-4 by this date to maintain the exemption.
Q2 — April through June
Apr 15
Individual returns due (Form 1040)Tax Day 2026. File your 2025 federal return or request an automatic 6-month extension (Form 4868). An extension to file is NOT an extension to pay.
Apr 15
IRA contributions deadline for 2025Last day to make traditional or Roth IRA contributions that count toward the 2025 tax year.
Apr 15
Q1 2026 estimated tax payment dueFirst installment of 2026 estimated taxes for self-employed individuals and those with non-W-2 income.
Jun 16
Q2 2026 estimated tax payment dueSecond installment of 2026 estimated taxes. Note: the Q2 period is shorter (Apr 1 to May 31).
Q3 — July through September
Sep 15
Q3 2026 estimated tax payment dueThird installment of 2026 estimated taxes (covers Jun 1 through Aug 31).
Q4 — October through December
Oct 15
Extended individual returns dueFinal deadline for 2025 individual returns if you filed a 6-month extension in April. This cannot be extended further.
Dec 31
Year-end tax strategy deadlineLast day to complete most year-end tax moves: Roth conversions, charitable contributions, loss harvesting, and retirement plan contributions (for most plan types).
Source: IRS Publication 509 and irs.gov tax calendar. Dates shift annually due to weekends and federal holidays. This page is updated each November for the coming year. Idaho generally follows federal income tax deadlines — confirm state-specific dates at tax.idaho.gov. Last updated: January 2026.
Q1 — January through March
Jan 15
Q4 2025 estimated tax payment dueFinal 2025 estimated payment for business owners and self-employed individuals with pass-through income.
Feb 2
1099-NEC forms due to contractors AND to IRSBoth the contractor copy and the IRS filing are due by February 2 (Jan 31 falls on a Saturday). File electronically whenever possible.
Mar 2
Paper 1099-MISC and other information returns filed with IRSPaper filing deadline for 1099-MISC, 1099-INT, 1099-DIV, and similar returns. Electronic deadline is March 31.
Mar 16
S-Corp (1120-S) and Partnership (1065) returns dueCalendar-year S corporations and partnerships must file or request a 6-month extension by this date (March 15 falls on a Sunday in 2026).
Mar 31
Electronic information returns due with IRSElectronic filing deadline for 1099-MISC, 1099-K, 1098, and other information returns — extended from the paper deadline.
Q2 — April through June
Apr 15
C-Corp (1120) returns dueCalendar-year C corporations must file or request a 6-month extension. Q1 estimated payments are also due.
Apr 15
Q1 2026 business estimated tax paymentFirst installment of 2026 estimated taxes for pass-through business income.
Jun 16
Q2 2026 business estimated tax paymentSecond installment of 2026 estimated taxes.
Q3 — July through September
Sep 15
Extended S-Corp and Partnership returns dueFinal deadline for 2025 S-Corp (1120-S) and Partnership (1065) returns if you filed a 6-month extension in March.
Sep 15
Q3 2026 business estimated tax paymentThird installment of 2026 estimated taxes.
Q4 — October through December
Oct 15
Extended C-Corp returns dueFinal deadline for 2025 C-Corp returns (Form 1120) if you filed a 6-month extension in April.
Dec 31
Year-end business tax strategiesLast day for deductible equipment purchases (Section 179), retirement plan funding (some plans), year-end bonus accruals, and most other year-end tax planning strategies.
Source: IRS Publication 509 and irs.gov tax calendar. Dates shift annually due to weekends and federal holidays. This page is updated each November for the coming year. Idaho generally follows federal income tax deadlines — confirm state-specific dates at tax.idaho.gov. Last updated: January 2026.
