December is too late to realize you're $8,000 short of maxing out your 401(k). This checklist walks you through the five things to check in October or November, while you still have enough paychecks to close the gap.
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Log into your plan provider or check your latest pay stub. Find the "YTD Employee Deferrals" number. This is how much you've contributed so far this year. Write it down.
Subtract your YTD contributions from the 2026 limit: $24,500 (under 50) or $32,000 (50+). If you're already on track, you're done. If there's a gap, move to step 3. For the full breakdown, see the 2026 contribution limits.
How many paychecks do you have left before December 31? Divide the gap by that number. That's the per-paycheck amount you need to defer. If it's more than you can afford, contribute what you can. Every dollar above the match threshold still compounds tax-advantaged.
Submit the change through your HR portal or plan provider. Most plans let you change your rate at any time. Changes take 1-2 pay periods to process, so don't wait until the last paycheck.
Check your plan's matching formula (e.g., 50% of the first 6% of salary). Make sure your deferral rate meets the threshold. Ask HR whether your plan does a "true-up" at year-end. If it doesn't, you need to contribute enough in every paycheck, not just the last few.
If you're paid biweekly, you have roughly 5-6 paychecks left in October. That's enough to spread out a meaningful increase without cutting your take-home pay in half for one month. By December, you might have 2 paychecks left, and the math gets painful.
gap to close? Over 5 paychecks that's $1,600 each. Over 2 paychecks it's $4,000 each.
pay periods for most employers to process a deferral rate change. Start in October, it's active by early November.
of participants miss the full employer match. Most of them planned to fix it "later."
Financial Engines / Alight, 2023
A 401(k) deadline reminder set for late October gives you the exact nudge this checklist is built for.
Ask your HR department one question: "Does our plan do a year-end true-up on the employer match?"
If yes, you can safely increase contributions in the last few months without worrying about missing match in earlier paychecks. If no, your match is calculated per paycheck. That means contributing 0% for six months and then 24% for the remaining months could cost you half the match, even though you hit the annual limit.
This single answer changes your year-end strategy. It takes 30 seconds to ask.
October or early November. You need at least 2-3 remaining paychecks to adjust your deferral rate. Changes submitted in December may not process in time for the final paycheck of the year.
Log into your plan provider's portal (Fidelity, Vanguard, Empower, Schwab) or check your latest pay stub. Look for "YTD Employee Deferrals" or "YTD 401(k) Contributions." This number is your starting point for calculating the gap.
Yes. Most plans allow contribution rate changes at any time. Submit the change through your HR portal or plan provider. Changes typically take effect within 1-2 pay periods. Some employers process changes faster than others.
Contribute at least enough to get the full employer match. For a typical 50% match on 6% of salary, that means contributing 6% of your pay. Anything below that is leaving free money on the table. You can always increase later in the year if cash flow improves.
Not all employers do. A "true-up" means the employer recalculates match at year-end to ensure you got the full amount, even if your contribution rate varied throughout the year. Check with HR. If your plan doesn't true-up, you need to contribute evenly across all paychecks to capture the full match.
If you hit the $24,500 limit early in the year, contributions stop automatically. Without a true-up, you may miss match in the remaining paychecks because there are no deferrals to match. Front-loading works best if your employer does a year-end true-up.
Set a free reminder for late October. Run this checklist, adjust your deferral, and close the gap before December 31.
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