Tax Planning · October 2026
The extended filing deadline is the finish line for last year's return and the starting line for this year's plan. Clients who use both dates well avoid penalties now and surprises in April.
For individuals who filed an extension in April, October 15 is the last day to file a 2025 federal return without a failure to file penalty. There is no second extension. Once the date passes, the IRS assesses 5% of the unpaid tax for each month the return is late, up to 25%.
An extension never extended the time to pay. Any balance due since April 15 has been accruing interest and a failure to pay penalty of 0.5% per month. Filing on time stops the larger penalty from stacking on top of the smaller one.
Self-employed clients and business owners: October 15 is also the deadline to fund a SEP IRA contribution for 2025 when the return is on extension. Missing the date forfeits the deduction for the year.
ZSS needs every outstanding item in hand before a return can be finalized and filed. If any of these are still on your desk, send them this week.
| Item | Why It Matters |
|---|---|
| Corrected or late 1099s and K-1s | Partnership and trust income often arrives late and changes the final numbers. |
| Signed e-file authorization (Form 8879) | ZSS cannot transmit your return without it. |
| Estimated payment records for 2025 | Unreported payments overstate your balance due. |
| Retirement contribution confirmations | SEP and other deductible contributions must be documented on the return. |
| Answers to open preparer questions | Unresolved questions are the most common reason a return stalls in the final week. |
A tax projection estimates what you will owe for the current year based on your actual income, withholding, and payments to date. It turns April from a surprise into a known number.
The weeks right after October 15 are the ideal window. Your 2025 return is complete and fresh, it serves as the baseline for your 2026 numbers, and there is still enough of the year left to change the outcome. A projection run in December leaves almost no room to act. A projection run in late October leaves eleven weeks.
2026 is also a year worth checking closely. The One Big Beautiful Bill Act changed several deductions and limits, and some of its provisions, including new rules for charitable giving, take effect for the first time this year. Last year's approach to your taxes may not produce last year's result.
Raises, bonuses, business growth, stock sales, and rental activity all move your bracket. ZSS models the full year, not just what has posted so far.
ZSS confirms whether your paycheck withholding and quarterly payments meet the safe harbor rules that prevent underpayment penalties.
ZSS tests whether itemizing still beats the standard deduction for you and applies the 2026 changes to state and local taxes, charitable gifts, and more.
Retirement contributions, equipment purchases, gain and loss harvesting, and the timing of income and expenses. Each one has a December 31 cutoff.
Safe harbor in brief: you generally avoid an underpayment penalty if your 2026 withholding and estimates cover 100% of your 2025 tax, or 110% if your 2025 adjusted gross income exceeded $150,000. A projection tells you exactly where you stand against that target.
Send any remaining documents and your signed Form 8879 so ZSS can file ahead of the deadline.
Extended 2025 returns filed. SEP IRA contributions for 2025 funded.
Schedule your 2026 projection. ZSS reviews year-to-date income and payments and identifies planning opportunities.
Deadline for most year-end moves, including 401(k) deferrals, charitable gifts, and harvesting gains or losses.
Fourth quarter estimated payment due, sized to the number your projection produced.
Zivetz, Schwartz & Saltsman CPAs has guided clients through deadlines for more than 50 years. Send your final documents now and reserve your 2026 projection before the calendar fills.
This article is for general information only and does not constitute tax advice. Tax outcomes depend on individual circumstances. Contact ZSS at (310) 826-1040 or info@zss.com to discuss your situation.