December 31 is the cutoff. Your 401(k) contributions come from payroll, so if you haven't increased your deferral rate by the last pay period, the year's limit is gone. No lump-sum catch-up. No extension. A reminder in November gives you time to adjust.
Done in seconds. No sign-up required.
The December 31 deadline doesn't come with a second chance.
the 2026 employee deferral limit, permanently lost if you don't contribute before year-end
IRS, 2026
what one missed $24,500 contribution could grow to over 25 years at a 6.5% average annual return
Compound growth calculation
of 401(k) participants don't contribute enough to get the full employer match, leaving free money on the table
Financial Engines / Alight, 2023
Unlike an IRA, you can't log into your brokerage on December 30 and make a lump-sum contribution. 401(k) contributions come from payroll. That means your actual deadline is your last paycheck of the year, which could be mid-December or even earlier.
Most people plan to "increase it later." January is too early to think about year-end. By October, open enrollment takes all the attention. November is holidays. Then it's December 15, you realize you're only at 60% of the limit, and there aren't enough paychecks left to make up the difference.
HR won't chase you. Your plan administrator sends a benefits packet once a year, not a personal nudge when you're falling behind on contributions. A reminder in October or November gives you the 2-3 pay periods you need to bump your deferral rate.
Enter "401(k) Contribution Deadline" and December 31. It takes 15 seconds. The reminder recurs every year.
You receive an email days before year-end. Enough time to check your year-to-date contributions, calculate the gap, and adjust your deferral rate.
If you don't mark it complete, you get follow-up emails. The reminder doesn't quietly disappear after one notification.
Limits, consequences, and what to check before December 31.
You can't make up missed 401(k) contributions. The limit doesn't roll over. Here's the real cost of falling short, calculated over decades of compounding.
See the full cost →Employee deferrals, catch-up contributions, employer match limits, and the combined ceiling. Know your numbers before adjusting your payroll.
Check 2026 limits →Self-employed? Your deadlines are different. Employee deferrals are due Dec 31, but employer contributions follow your tax filing deadline.
See solo 401(k) dates →Everything around the December 31 deadline.
For employee salary deferrals, the deadline is December 31 of each calendar year. Your last paycheck of the year is your final chance to contribute. Employer contributions (matching and profit-sharing) have until the company's tax filing deadline, including extensions.
No. Employee 401(k) contributions must come from payroll deductions, so December 31 is a hard cutoff. Unlike an IRA, you cannot make a lump-sum contribution after the year ends. If you didn't max out, that year's unused limit is gone.
The 2026 employee deferral limit is $24,500 if you are under 50. If you are 50 or older, you can add a $7,500 catch-up contribution for a total of $32,000. The combined employee plus employer limit is $70,000.
No. Employer matching contributions do not count against your $24,500 employee deferral limit. They count toward the overall combined limit ($70,000 in 2026), but that ceiling is rarely hit for most employees.
Excess contributions must be withdrawn by April 15 of the following year, or you'll be taxed twice on that amount. Your plan administrator should catch this, but if you have multiple 401(k) plans, you're responsible for tracking the total yourself.
Yes. Roth 401(k) contributions share the same December 31 deadline and the same $24,500 limit. The difference is in tax treatment (after-tax contributions, tax-free withdrawals), not the deadline. Traditional and Roth 401(k) contributions share one combined limit.
Free. No account. Set a reminder before December 31 and actually max out your 401(k) this year.
Set My 401(k) Deadline ReminderLast modified: