Year-End Tax Planning 2026: 4 Dates That Can Still Lower Your Tax Bill

Year-end tax planning 2026 comes down to four dates. Most of the moves that cut your 2026 tax bill have a hard deadline, and once it passes there's nothing your preparer can do about it in March. Here's what to do by each date, with the 2026 limits the IRS has published.

Oct. 15, 2026: extended returns and the last 2025 SEP-IRA

If you filed an extension for your 2025 return, Thursday, Oct. 15, 2026 is the final deadline. New Jersey and New York extended returns are due the same day.

Self-employed and on extension? A SEP-IRA for 2025 can be set up and funded as late as the due date of your return, including extensions. That makes Oct. 15 your last chance to lower your 2025 tax with a retirement contribution.

Dec. 31, 2026: the cutoff for most tax-saving moves

This is the date that matters most. Each of these has to happen in 2026 to count on your 2026 return.

Charitable gifts, with a new rule for 2026

Starting with 2026, you can deduct up to $1,000 of cash gifts to qualifying charities ($2,000 if married filing jointly) even if you take the standard deduction. Before, only people who itemized got a deduction for giving. Keep the receipt, and give in cash (check, card or transfer) rather than goods.

Prepay spring 2027 tuition

Tuition you pay in 2026 for an academic period that starts in the first three months of 2027 counts toward a 2026 education credit, such as the American opportunity credit. If the 2026 credit isn't maxed out, paying the spring bill in December can help.

529 contributions for a state deduction

There's no federal deduction for 529 contributions, but many states give one. New Jersey lets you deduct up to $10,000 of contributions to an NJBEST account if your gross income is $200,000 or less. New York lets you deduct up to $5,000 ($10,000 married filing jointly) for contributions to New York's 529 College Savings Program. Both count contributions made by Dec. 31.

Required minimum distributions

If you're 73 or older, take your 2026 required minimum distribution from IRAs and retirement plans by Dec. 31. (Your first one can wait until April 1 of the following year, but then you take two in one year.)

401(k) deferrals through payroll

Employees can defer up to $24,500 into a 401(k) for 2026, plus $8,000 if 50 or older ($11,250 if 60 to 63). Deferrals come out of paychecks, so they have to run through 2026 payroll. That includes S-corp owners paying themselves a salary.

Jan. 15, 2027: fourth-quarter estimated tax

The fourth-quarter 2026 estimated payment is due Friday, Jan. 15, 2027. That's the one to watch if you're self-employed, had a big capital gain, or sold a business asset late in the year. Most states, including New Jersey and New York, use the same date for their fourth-quarter estimates.

April 15, 2027: IRA, HSA and the Solo 401(k) most people don't know about

The Solo 401(k) rule: since the SECURE 2.0 Act, a sole proprietor with no employees (other than a spouse) can open a brand-new Solo 401(k) after year-end and still make first-year employee deferrals for 2026, up to the due date of the return without extensions. For most people that's April 15, 2027. It's one of the few big retirement moves you can still make after Dec. 31.

How to use these year-end tax planning dates

1. Look at your 2026 income now, not in March. Most of the savings above need action by Dec. 31.
2. Check your withholding and estimates before Jan. 15 so there's no underpayment penalty surprise.
3. Pick the right retirement account for your situation: SEP-IRA, Solo 401(k), traditional IRA or Roth IRA.
4. Save the dates. Add them to your calendar with the links below, or subscribe to the MFA key-dates calendar so new deadlines show up on their own.

Running a business too? Our Section 179 vs. bonus depreciation guide covers the Dec. 31 equipment deadline, and our Form 1099 guide covers what's due in January.

Quick answers

What is the 2026 IRA contribution limit?

$7,500, or $8,600 if you're 50 or older. You have until April 15, 2027 to contribute for 2026.

What is the 2026 HSA contribution limit?

$4,400 for self-only coverage and $8,750 for family coverage, plus $1,000 if you're 55 or older. The deadline for 2026 contributions is April 15, 2027.

What is the solo 401(k) deadline for 2026?

A sole proprietor with no employees can open a new Solo 401(k) and make first-year 2026 deferrals until the return due date without extensions, usually April 15, 2027.

When is the fourth quarter estimated tax payment due?

The fourth quarter estimated tax payment for 2026 is due January 15, 2027.

Can I deduct charity if I don't itemize in 2026?

Yes. Starting in 2026, non-itemizers can deduct up to $1,000 of cash gifts to qualifying charities, or $2,000 if married filing jointly.

Is there a 529 tax deduction in New Jersey and New York?

Yes. New Jersey allows up to $10,000 for NJBEST contributions if gross income is $200,000 or less. New York allows up to $5,000 ($10,000 joint) for its 529 College Savings Program.

Merchant Financial Advisory (MFA), an accounting and tax solutions provider in Princeton, New Jersey, helps individuals and small and mid-sized businesses in New Jersey, New York and nationwide plan before year-end. See our tax planning services, or book a call below.