Year-End Tax Planning Checklist 2026
Year-End Tax Planning Checklist 2026
The final quarter of the year represents the last window to reduce your 2026 tax bill. Every dollar you shelter, harvest, or redirect between October and December 31 is a dollar that compounds in your favor rather than funding the Treasury. This checklist walks you through month-by-month actions so nothing falls through the cracks.
Data Notice: Tax figures in this article reflect projected 2026 values based on IRS inflation adjustments and provisions of the One Big Beautiful Bill Act. Figures marked with ~ are estimates. Confirm all numbers with official IRS publications before filing.
Why Year-End Tax Planning Matters
Most taxpayers think about taxes only when they sit down to file in the spring. By then, the game is already over. Year-end planning is proactive: you still have time to make contributions, realize losses, shift income, and lock in deductions before the calendar flips.
The stakes are particularly high in 2026 because of the One Big Beautiful Bill tax changes signed into law, which made permanent many provisions that were set to expire and introduced several new deductions. Understanding how these changes affect your specific situation is essential to optimizing your year-end moves.
Key benefits of year-end planning include:
- Lower marginal tax rate by shifting income or accelerating deductions
- Maximized retirement savings by topping off contribution limits
- Reduced investment taxes through strategic loss harvesting
- Optimized charitable impact by timing donations for maximum deduction value
- Avoided penalties by truing up estimated tax payments
October Action Items
October is the strategy month. You still have roughly 90 days, enough time to execute complex moves without rushing.
Review Your Year-to-Date Tax Picture
Pull together your income, withholdings, and estimated payments so far. Compare them against the 2026 tax brackets to see which bracket you are in and how close you are to the next one. This single exercise drives every other decision on this checklist.
If you use tax software, run a projection with your year-to-date numbers plus expected income for the remaining months. If you work with a CPA, schedule a planning call now before their calendars fill up.
Evaluate Retirement Contribution Room
Check your 401(k) contributions against the 2026 contribution limits. The employee deferral limit is ~$23,500 for those under 50 and ~$31,000 for those 50 and older. If you are behind, calculate the per-paycheck increase needed to max out by December 31.
For IRAs, the contribution limits are ~$7,000 (under 50) and ~$8,000 (age 50+). You technically have until April 15, 2027, to make IRA contributions for 2026, but starting the analysis now prevents last-minute scrambles.
Assess Capital Gains and Losses
Review your taxable investment portfolio for unrealized gains and losses. A tax-loss harvesting strategy can offset gains dollar-for-dollar, with up to ~$3,000 in excess losses deductible against ordinary income.
October is ideal for harvesting because you can reinvest after the 30-day wash-sale window and still have time for the replacement position to recover before year-end reporting. Review your capital gains tax strategies to understand which gains are short-term versus long-term and how harvesting changes the math.
Check HSA Contribution Status
If you have a high-deductible health plan, verify your HSA contributions against the 2026 limits of ~$4,300 (individual) and ~$8,550 (family). HSA contributions are the only triple-tax-advantaged savings vehicle in the tax code: deductible going in, tax-free growth, and tax-free withdrawals for qualified medical expenses.
If your employer contributes to your HSA, subtract that amount from the annual limit to determine your remaining contribution room.
November Action Items
November is execution month. The decisions made in October should now translate into concrete actions.
Max Out Retirement Contributions
If you determined in October that you need to increase 401(k) deferrals, confirm the payroll change has taken effect. Most employers process changes within one to two pay periods, so November is the last comfortable window.
For self-employed individuals with Solo 401(k) plans or SEP-IRAs, calculate your expected net self-employment income to determine the maximum employer contribution. These plans often allow contributions well into the following year, but having the calculation ready now avoids surprises.
Execute Tax-Loss Harvesting Trades
If you identified positions with unrealized losses in October, November is prime execution time. Sell the losing positions, and reinvest in similar (but not “substantially identical”) securities to maintain your asset allocation. Remember:
- The wash-sale rule prohibits repurchasing substantially identical securities within 30 days before or after the sale
- Selling a total U.S. stock market fund and buying an S&P 500 fund is generally acceptable
- Harvested losses offset capital gains first, then up to ~$3,000 of ordinary income
- Unused losses carry forward indefinitely
Plan Charitable Contributions
Decide whether you will take the standard deduction or itemize this year. The standard deduction for 2026 is ~$30,000 for married couples filing jointly and ~$15,000 for single filers. The new ~$6,000 senior tax deduction stacks on top for those 65 and older.
If your total itemizable expenses are close to the standard deduction threshold, consider a bunching strategy where you accelerate two years of charitable giving into one tax year to push past the threshold.
For taxpayers over 70 and a half with IRAs, a Qualified Charitable Distribution of up to ~$105,000 directly from your IRA to a qualifying charity counts toward your Required Minimum Distribution while being excluded from income entirely.
Open Enrollment Decisions
Open enrollment season is also a tax planning opportunity:
- HSA-eligible plan: Choosing a high-deductible health plan for 2027 opens up HSA contributions starting January 1
- FSA elections: Use-it-or-lose-it rules mean you should estimate 2027 medical and dependent care expenses carefully
- Employer stock purchase plans: Evaluate whether to participate or increase participation based on discount and tax treatment
December Action Items
December is the deadline month. Every action item here must be completed by December 31 unless otherwise noted.
Final Retirement Contribution Push
Confirm your final December paychecks will include the 401(k) deferrals needed to hit your limit. If your employer offers a mega backdoor Roth option with after-tax contributions and in-plan Roth conversions, ensure those are also on track.
Make Charitable Donations
All charitable contributions must be completed by December 31 to count for the 2026 tax year. For cash donations, the date the check is mailed or the credit card is charged determines the tax year. For stock donations, the transfer must be initiated with enough lead time for the brokerage to complete it.
If you are donating appreciated stock held longer than one year, you avoid capital gains tax on the appreciation and deduct the full fair market value. This is one of the most tax-efficient ways to give. Review the charitable deduction guide for AGI percentage limits.
Roth Conversion Window
If you expect to be in a lower tax bracket this year than in future years, a Roth conversion before December 31 lets you pay tax at today’s lower rate and enjoy tax-free growth going forward. Common scenarios:
- Year of retirement with partial-year income
- Sabbatical or career break
- Year with large capital losses offsetting income
- Gap year before Social Security begins
Be precise about the conversion amount. Converting too much can push you into a higher bracket, trigger the Net Investment Income Tax (3.8%), or increase Medicare IRMAA surcharges two years later.
Estimated Tax True-Up
If you owe estimated taxes, the fourth quarter payment is due January 15, 2027, but paying before December 31 may provide a deduction benefit in certain situations. More importantly, verify that your total payments (withholding plus estimated) meet the safe harbor to avoid underpayment penalties:
- 100% of prior year tax liability, or
- 90% of current year tax liability
- For high earners (AGI over ~$150,000): 110% of prior year tax liability
SALT Deduction Optimization
Under the One Big Beautiful Bill, the SALT deduction cap increased to ~$40,000 for married filing jointly. If you live in a high-tax state, evaluate whether prepaying January property taxes in December helps you maximize the new cap. However, do not prepay state income taxes for 2027, as the IRS has historically disallowed premature state tax prepayments.
Required Minimum Distributions
If you are 73 or older, your Required Minimum Distribution must be taken by December 31 (not April 15, which only applies to the first RMD year). Missing the deadline triggers a 25% excise tax on the amount not distributed.
Gifting and Estate Planning
The federal gift tax annual exclusion is ~$19,000 per recipient for 2026. If you have been making annual exclusion gifts to family members, complete them before December 31. The permanent estate tax exemption under the OBBB provides long-term planning certainty, but annual gifting remains a core wealth transfer strategy.
Trump Account Contributions
The new Trump Account (MAGA Account) created by the One Big Beautiful Bill offers tax-free growth on up to ~$5,000 in annual contributions for newborns and children. If you had a child in 2026 or have eligible children, fund the account before year-end to begin the tax-free compounding.
Quick-Reference Calendar
| Deadline | Action |
|---|---|
| October 1-15 | Run tax projection; schedule CPA meeting |
| October 15 | Extended return deadline for 2025 |
| October 15-31 | Increase 401(k) deferrals; identify harvest candidates |
| November 1-15 | Execute tax-loss harvesting trades |
| November 15-30 | Plan and initiate charitable contributions |
| December 1-15 | Roth conversions; stock donations; estimated tax review |
| December 31 | Hard deadline: RMDs, charitable gifts, SALT prepayments, retirement plan contributions (employer plans) |
| January 15, 2027 | Q4 estimated tax payment due |
| April 15, 2027 | IRA contribution deadline for 2026 |
Common Mistakes to Avoid
Waiting until December 31. Brokerage transfers, stock donations, and payroll changes take time to process. Start complex transactions by December 15 at the latest.
Ignoring the wash-sale rule. If you harvest a loss and repurchase a substantially identical security within 30 days, the loss is disallowed. This includes purchases in your IRA or spouse’s account.
Over-converting to Roth. Running a precise projection before converting prevents accidentally pushing yourself into a higher bracket or triggering IRMAA surcharges.
Forgetting state tax implications. Federal and state tax planning do not always align. A move that saves federal taxes could increase state taxes, particularly in states without a Roth conversion exemption.
Missing the RMD deadline. The 25% penalty for missed RMDs is steep. Set a calendar reminder for early December.
Frequently Asked Questions
What is the single most impactful year-end tax move?
For most employed taxpayers, maximizing 401(k) contributions delivers the largest immediate tax savings. Each dollar contributed to a traditional 401(k) reduces taxable income dollar-for-dollar. At a 24% marginal rate, maxing out the ~$23,500 limit saves ~$5,640 in federal taxes alone.
Can I still make IRA contributions after December 31?
Yes. IRA contributions for the 2026 tax year can be made until April 15, 2027. However, 401(k) employee deferrals must come from payroll and cannot be made after December 31.
Is it too late to do a Roth conversion in December?
No. A Roth conversion can be executed on any business day up to December 31. However, if your brokerage requires additional processing time for transfers between accounts, initiate the conversion by mid-December to ensure it settles in 2026.
How do I know if I should itemize or take the standard deduction?
Add up your potential itemized deductions: state and local taxes (capped at ~$40,000), mortgage interest, charitable contributions, and medical expenses exceeding 7.5% of AGI. If the total exceeds the standard deduction for your filing status, itemizing saves you more.
What if I cannot afford to max out my 401(k)?
Contribute at least enough to capture any employer match, which is an immediate 50-100% return on your money. Then prioritize an HSA if eligible, followed by IRA contributions. Every additional dollar of tax-advantaged savings reduces your current tax bill and grows tax-free or tax-deferred.
Does the new SALT cap of $40,000 change year-end planning?
Significantly. Under the previous $10,000 cap, many taxpayers in high-tax states could not itemize because the cap limited their largest deduction. The ~$40,000 cap restores much of the deduction’s value, making it worthwhile to re-evaluate whether itemizing beats the standard deduction. Review the SALT deduction details for income-based phaseout rules.
Bottom Line
Year-end tax planning is a disciplined process, not a last-minute scramble. By breaking the work into October (strategy), November (execution), and December (deadline compliance), you can systematically capture every available deduction, credit, and deferral. The tax filing deadlines for 2026 give you until April to file, but December 31 is when the real decisions lock in.
This article is for informational purposes only and does not constitute tax advice. Tax laws are complex and subject to change. Projected figures (marked with ~) are estimates based on current legislation and IRS inflation adjustments. Consult a qualified tax professional before making tax planning decisions.