Guide
The 2026 Tax Planning Calendar.
Every federal tax deadline for 2026 with plain language notes on what to actually do each quarter. Bookmark this and check back.
A quick note: these are federal deadlines. State deadlines often mirror the federal ones but not always. If a deadline lands on a weekend or federal holiday, the IRS usually moves it to the next business day. Confirm your state calendar with me or check your state's department of revenue.
January through March 2026.
| Date | Deadline | What to do |
|---|---|---|
| Jan 15, 2026 | 4th quarter 2025 estimated tax due (individuals) | Pay your Q4 2025 estimate if you're self employed, a business owner, or had significant unwithheld income last year. |
| Jan 31, 2026 | W 2s and 1099s due to recipients | Employers send W 2s to employees. Businesses issue 1099 NEC to contractors paid $600 or more in 2025. Copy A of 1099 NEC also due to the IRS. |
| Mar 17, 2026 | Partnership and S corp returns due (2025) | Form 1065 and Form 1120 S are due. File or extend. Don't forget K 1s to partners and shareholders so they can file their personal returns on time. Normally March 15 but it falls on a Sunday in 2026. |
April through June 2026.
| Date | Deadline | What to do |
|---|---|---|
| Apr 15, 2026 | Individual and C corp returns due (2025) | Form 1040 and Form 1120 are due. File or file Form 4868 (individuals) or Form 7004 (C corps) for an extension. Extension extends time to file, not time to pay. |
| Apr 15, 2026 | 1st quarter 2026 estimated tax due | Q1 2026 estimate for self employed and business owners. Pay even if you extended the return. |
| Apr 15, 2026 | IRA, HSA, and Roth contribution deadline (for 2025) | Last day to fund 2025 IRA or HSA. SEP IRA funding for 2025 can go until the extended business return due date. |
| Jun 15, 2026 | 2nd quarter 2026 estimated tax due | Q2 estimate. Yes, it's only two months after Q1. The IRS' schedule is quirky like that. |
July through September 2026.
| Date | Deadline | What to do |
|---|---|---|
| Sep 15, 2026 | 3rd quarter 2026 estimated tax due | Q3 estimate. If income spiked in the first half of the year, consider topping up now. |
| Sep 15, 2026 | Extended partnership and S corp returns due (2025) | Final deadline for Form 1065 and Form 1120 S on extension. After this, late filing penalties start stacking. |
| Late Sep 2026 | Mid year tax projection (recommended) | This isn't an IRS deadline. It's a planning moment. Run your year to date numbers and project the full year so you're not surprised. |
October through December 2026.
| Date | Deadline | What to do |
|---|---|---|
| Oct 15, 2026 | Extended individual and C corp returns due (2025) | Final deadline for Form 1040 and Form 1120 on extension. |
| Dec 31, 2026 | Year end cutoff for 2026 planning moves | Last day for many planning actions: charitable contributions, retirement plan setups (for 2026), business purchases for depreciation, Roth conversions, and more. After Jan 1, you're working with 2027. |
| Dec 31, 2026 | Solo 401k plan established by year end | If you're self employed and want a solo 401k for 2026, the plan must be established by December 31. Contributions can go in later. |
What to actually do each quarter.
Not every quarter needs heroics. Here's what a healthy rhythm looks like for most of my clients.
Every quarter
- Reconcile books through the end of the prior quarter.
- Run a profit and loss report and compare to last year.
- Pay estimated taxes if you owe them.
- Log any big personal life changes for me (marriage, baby, house, move).
Before year end
- Run a full year tax projection.
- Max out retirement contributions where possible.
- Review charitable giving and timing.
- Confirm 1099 contractor info before January rush.
- Book your tax prep slot for the next season.
This calendar is general information, not tax advice for your specific situation. Any tax advice contained here is not intended to be used, and cannot be used, for the purpose of avoiding penalties imposed by the Internal Revenue Code.
Your calendar. Your numbers. Our rhythm.
Advisory clients get quarterly check ins built around these dates. We stay ahead of every one of them together.
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