Understand your plan's rules

Look up your plan's match formula in your summary plan description or benefits portal (e.g., "100% of the first 4% of pay").
Find out whether your plan matches every paycheck ("per-pay-period") or based on total pay for the year.If it's per-pay-period, front-loading your contributions early in the year can mean you hit your own deferral limit before the match dollars stop flowing on later paychecks — costing you match, unless a true-up applies.
Ask HR or your plan provider whether the plan has a "true-up" provision.If your plan calculates the employer match based on each payday contribution, adding a true-up provision means at year-end the employer makes good on the full promise of the match, regardless of when employees reached the annual contribution limit. Without one, maxing out early can permanently cost you match money.
Confirm this year's employee deferral limit.The standard annual deferral limit for 2026 is $24,500.
If you're 50 or older, add the catch-up. if age 50 or olderThe catch-up contribution limit for those age 50 and older is $8,000 for 2026.
If you're turning 60–63 this year, check for the "super" catch-up. if turning 60 to 63If you're in this age group, you can contribute up to $11,250 to your 401(k), 403(b), or governmental 457 plan for 2026, far above the standard catch-up amount. This is optional for employers, so confirm your plan actually offers it before you count on it.
If you earn $160,000 or more, ask whether nondiscrimination testing could limit you. if earns 160k or moreThe IRS defines a highly compensated employee as anyone earning $160,000 or more, and if a plan fails nondiscrimination testing, HCE contributions may need to be reduced or refunded. Safe harbor plans avoid this issue, so find out which type yours is.

Do the math

Pull your year-to-date contribution total from your latest pay stub or plan account.
Count how many paychecks remain in the plan year.Payroll cutoffs often fall a few days before December 31, not on the actual last day.
Divide your remaining room (limit minus what you've already put in) by the paychecks left, to find the per-paycheck contribution that lands you right at the limit.
If your plan has no true-up, recalculate so your final contribution lands on the last paycheck of the year, not earlier.Stopping early with no true-up means forfeited match with no way to recover it.
If you can't realistically reach the full IRS limit in the time left, prioritize contributing enough each remaining paycheck to capture the full match percentage first. if cant reach full limitEven if you can't hit the max.

Make the change

Submit your new contribution percentage or dollar amount through payroll or your plan portal well before the next pay cycle's processing cutoff.Most systems need changes days ahead of payday, not the day of.
Check your very next pay stub to confirm the new rate actually applied before assuming it's set.
If your plan offers both Roth and pre-tax contributions, decide how to split what's left. if plan offers roth and pretaxThe combined total — not each type separately — counts toward your IRS limit.
If you're a high earner making catch-up contributions once the new Roth catch-up rule takes effect, check with payroll on how it's handled. if high earner catch up 2026SECURE 2.0 requires catch-up contributions for high earners (prior-year wages above $150,000) to be made on a Roth basis starting in 2026.
Avoid setting your rate too high late in the year.Payroll systems can cap or reject a paycheck's deduction if it would exceed what's left of your limit, throwing off your final total.

Confirm the employer money shows up

Watch your plan statement for the true-up deposit, if your plan has one.Employers handle true-ups differently — many wait until after the plan year has ended before they process true-up payments, while others make true-up matching contributions throughout the year.
Check your Q1 statement to confirm the match matches the formula for the full year, not just what showed up per paycheck.
If a promised true-up doesn't appear, contact HR or your plan administrator with pay stubs as backup. if true up missingIt won't necessarily self-correct.
If you over-contributed past the IRS limit (common if you switched jobs mid-year), request a corrective distribution of the excess before the tax filing deadline. if over contributed past limitLeaving it in the plan risks it being taxed twice.

Set up next year

Write down your plan's match formula and true-up status somewhere you'll find it again.So you're not starting from scratch next year.
If you're a few years from turning 60, note the super catch-up eligibility for future planning. if few years from 60It's a meaningfully higher limit than the standard catch-up.
Revisit your contribution percentage in January against the new year's IRS limit.It typically rises slightly each year and last year's max-out rate may under-contribute this year.

Maxing Out Employer 401(k) Matching Before Year End

Understand your plan's rules

Do the math

Make the change

Confirm the employer money shows up

Set up next year