401(k) Max-Out Calculator
Updated September 2026 · Free · No sign-up
Calculate the per-paycheck contribution needed to max out your 401(k) by December 31 — the 2026 $24,500 limit, catch-up at 50+, and the year-end sprint math from wherever you are today.
Quick answer: The 2026 401(k) employee limit is $24,500 ($32,500 with the 50+ catch-up). To max out: (limit − contributed so far) ÷ paychecks left. $14,000 in with 7 biweekly checks remaining = $1,500 per check — set the new percentage in your plan portal this week; changes take 1-2 pay cycles.
The Formula
Per-check contribution = (Annual Limit − Year-to-Date Deferrals) ÷ Paychecks Remaining
Then convert to the percentage your plan portal wants: per-check amount ÷ gross pay per check. Deadline reality: 401(k) contributions must flow through payroll by December 31 — no April catch-up window like IRAs and HSAs — and portals take 1-2 cycles to apply changes, so the effective deadline is late November/early December.
Worked Examples
Example 1 — the October check-in. $14,000 deferred, under 50, 7 biweekly checks left: ($24,500 − $14,000) ÷ 7 = $1,500/check (39% of a $3,800 gross). Steep — which is why the smart version of this calculation happens in October, not December.
Example 2 — catch-up unlock. Turning 50 any day in 2026 unlocks the full $8,000 catch-up for the whole year — a 50th birthday in December still permits $32,500.
Example 3 — funded by the bonus month. A three-paycheck month in Oct-Dec is the cleanest max-out fuel: route the third check's slack into the deferral bump and monthly cash flow never feels it.
Should You Even Max Out? (The Priority Stack)
- Always: contribute to the full employer match — the match calculator prices the free money.
- High-interest debt gone, emergency fund funded?
- HSA next if HDHP-covered — the triple tax advantage beats the 401(k)'s double.
- Then max the 401(k) — $24,500 at the 24% bracket defers ~$5,880 of tax this year.
- Beyond: backdoor Roth IRA, then taxable.
The True-Up Trap (Read Before Front-Loading)
Maxing out early can forfeit match dollars: most plans match per-paycheck, so once your deferrals hit the cap and stop, the match stops too. A worker maxing by September loses 3 months of match unless the plan has a true-up provision (an annual reconciliation deposit). Check the plan document; no true-up → pace contributions to finish exactly at year-end — which is precisely the number this calculator gives you.
2026 Limits Reference
| Limit | 2026 |
|---|---|
| Employee deferral (401k/403b/most 457) | $24,500 |
| Catch-up (50+) | +$8,000 → $32,500 |
| Total annual additions (employee + employer) | $72,000 |
| IRA | $7,500 (+$1,100 catch-up) |
| Note | High earners ($150k+ prior-year FICA wages): catch-up contributions must be Roth (SECURE 2.0) |
2027 limits are announced by the IRS around November 2026 — recheck before setting January elections.
Traditional vs Roth for the Year-End Bump
The December deferral bump comes off your highest-taxed dollars — the marginal-rate logic from the overtime tax calculator applies in reverse, which favors traditional deferrals for the bump if you're in the 24%+ bracket, and Roth if you're in 12%. A big year-end bonus can also feed the deferral (bonus checks honor your 401(k) percentage in most plans) — one of the few ways to blunt bonus withholding.
Frequently Asked Questions
What is the 401(k) contribution limit for 2026?
$24,500 in employee deferrals; $32,500 with the 50+ catch-up ($8,000). The combined employee+employer cap is $72,000. 2027 limits arrive around November 2026.
How do I calculate what to contribute to max out?
(Limit − year-to-date deferrals) ÷ paychecks remaining, converted to a percentage of gross per check. Changes take 1-2 pay cycles to apply.
Can I contribute to my 401(k) after December 31?
No — 401(k) deferrals must run through payroll within the calendar year. Only IRAs and HSAs allow contributions until the April tax deadline.
Does the employer match count toward the $24,500?
No — the match counts only toward the $72,000 combined cap. Your deferral room is unaffected by employer contributions.
Is maxing out early a mistake?
It can forfeit match money in plans without a true-up, since per-paycheck matching stops when your deferrals stop. Pace to finish at year-end unless your plan trues up.
Do bonuses count toward maxing my 401(k)?
Usually yes — most plans apply your deferral percentage to bonus checks, making a December bonus an efficient max-out source (and reducing its withholding sting).
✓ Formula verified • Last updated: September 27, 2026