By Lauren Mitchell
The difference between a financially solid year and a painful April isn’t luck. It’s the last six weeks of December. Most of the tax-saving, account-optimizing, retirement-boosting moves that separate the financially savvy from everyone else have a hard deadline: December 31st at 11:59 PM.
Miss the window and you can’t go back. The IRS doesn’t care about your intentions. Your employer’s benefits portal locks. Your 401(k) contributions stop. The opportunity to shelter tens of thousands of dollars from taxes simply disappears until next year, and next year you’ll be one year closer to retirement with less runway to recover.
Here are the seven end-of-year moves that will save most people between $1,500 and $8,000 if you execute all of them. You don’t need a CPA to do any of these. You just need to know they exist and block out a Saturday to knock them out.
1. Max Out Your 401(k) Contribution
Your 401(k) contribution limit is use-it-or-lose-it. You can’t make up 2025’s contribution room in 2026. For 2025, you can put in up to $23,500 (or $31,000 if you’re 50 or older). If you’re not maxed out and you can afford to contribute more from your last few paychecks of the year, log into your benefits portal and bump your contribution rate up.
Every dollar you put in lowers your taxable income by a dollar, which typically saves you 22 to 37 cents in federal taxes alone, plus state taxes in most states. On the full $23,500, that’s $5,000 to $9,000 in tax savings. This is the single biggest end-of-year move most people fail to make.
2. Catch Any Employer Match You’re Leaving on the Table
Roughly 25 percent of employees fail to contribute enough to capture their full employer 401(k) match. That’s free money you’re declining every pay period. If your employer matches 50 percent of your contributions up to 6 percent of your salary, and you’re only contributing 3 percent, you’re losing 1.5 percent of your salary every year. On a $70,000 salary, that’s over $1,000 walking out the door.
Check your benefits portal this week. Confirm what the match formula is. Confirm what you’re contributing. If there’s a gap, fix it before the last payroll of the year. For more on the subtle habits that compound financial damage over time, see hidden money habits draining every dollar.
3. Use or Lose Your FSA Balance
If you have a Flexible Spending Account (FSA) through work for healthcare expenses, the funds in it typically expire on December 31st. Some plans have a grace period or a small carryover, but most don’t. If you don’t spend the money on eligible expenses, it’s gone. Forever.
Log into your FSA portal. Check the balance. Then schedule the dental cleaning you’ve been putting off, buy new prescription glasses, stock up on contact lenses, fill any prescriptions you need, or pay for eligible medical copays. FSA-eligible items also include things like sunscreen (SPF 30+), first aid supplies, thermometers, and even some over-the-counter medications.
4. Review and Rebalance Your Portfolio
If you have taxable investment accounts (not 401(k)s or IRAs), December is when tax-loss harvesting happens. This is the practice of selling investments that are down from their purchase price to realize the loss for tax purposes, then using that loss to offset capital gains you’ve realized elsewhere. You can also use up to $3,000 of net losses against ordinary income each year.
If you don’t have losses to harvest, December is still the right time to rebalance. If your target is 70 percent stocks, 30 percent bonds, and a great stock year has pushed you to 80/20, trim the stock position and move the money to bonds. This disciplined rebalancing is what the best investors do, and it forces you to sell high and buy low automatically.
5. Make Charitable Contributions (If You Itemize)
If you itemize deductions on your taxes, every dollar you donate to a qualified charity reduces your taxable income. The deadline is December 31st. Credit card donations made on New Year’s Eve count for this tax year even if you don’t pay the card bill until January.
If you own appreciated stock or mutual fund shares in a taxable account, consider donating them directly to a donor-advised fund or qualified charity instead of cash. You avoid paying capital gains tax on the appreciation and you still get the full fair-market-value deduction. This move alone can save high earners thousands of dollars on a $10,000 donation.
6. Set Up or Fund Your Traditional or Roth IRA
The IRA contribution deadline is technically April 15th of the following year, but funding it before December 31st gives the money more time to grow and, more importantly, makes sure you don’t forget. For 2025, the contribution limit is $7,000 ($8,000 if 50 or older).
Traditional IRAs give you a tax deduction today (income limits apply). Roth IRAs give you tax-free withdrawals in retirement (income limits also apply, but there’s a backdoor Roth strategy for high earners). Both are massive wealth-building tools most people underuse. If you haven’t funded yours this year, this is the move that might matter most in twenty years.
7. Review Your W-4 and Plan Next Year’s Withholding
Look at your last pay stub. Is your federal tax withholding way too high (meaning you’re getting a big refund every April) or way too low (meaning you owe the IRS)? Either way, the IRS isn’t your savings account. Adjust your W-4 now so that next year, the right amount comes out of each paycheck. For help thinking through whether you need a bigger shift in your financial approach next year, see broke professional paradox 80k salary.
Big refund people: you’ve been giving the government an interest-free loan all year. That’s money you could have invested or used to pay down high-interest debt. Owe-taxes people: you’re at risk of underpayment penalties. Adjust withholding now through your HR portal so January 2026 starts clean.
The Deadline Is Real. The Money Is Real.
Most people scroll past articles like this because the math feels abstract. It isn’t. These seven moves, executed consistently, are the difference between someone who retires at 62 and someone who works until 70. They’re the difference between owing the IRS and getting an unexpected refund. They’re the difference between building wealth silently in the background and starting every January feeling behind.
You don’t need to do all seven. Pick three and execute them before December 31st. Next year, pick four. Year after that, all seven become second nature. This is how financially stable people actually operate: they know the deadlines, they schedule the moves, and they don’t leave free money on the table.
Your Move This Week
Open a calendar right now and block two hours this Saturday titled “Year-End Money.” Pick the three moves above that apply to you. Work through them one at a time. You’ll finish in less time than it takes to watch a movie, and you’ll save more money than most people save by working overtime for a month. Tell me in the comments which three you picked, or share this with the friend who’s still catching up on April’s taxes.