To calculate your 403(b) contributions, multiply your gross annual salary by the percentage you want to defer, then divide by the number of pay periods in your year. The result is what comes out of each paycheck. Your total for 2026 cannot exceed the federal elective deferral limit of $24,500, unless you qualify for a catch-up that raises the ceiling. Employer matching is layered on top of your deferrals and follows a separate formula set by your plan.
The Basic Deferral Formula
Start with three numbers: your gross annual salary, the percentage (or flat dollar amount) you want to contribute, and your pay frequency.
If you earn $60,000 and choose to defer 10%, your annual contribution is $6,000. Divided across 24 semi-monthly pay periods, that’s $250 per paycheck. Biweekly at 26 pay periods, it’s roughly $231.
You can set a flat dollar amount per paycheck instead of a percentage. Flat amounts keep each deduction predictable when overtime or bonuses shift your gross pay, but you’ll need to adjust manually after a raise if you want the savings rate to keep up.
Whichever method you use, the annual total is what matters for the federal limit. Your elective deferrals for 2026 cannot exceed $24,500 across all your 403(b), 401(k), and SIMPLE accounts combined, not per plan.1Internal Revenue Service. How Much Salary Can You Defer if You’re Eligible for More Than One Retirement Plan If you contribute to a 401(k) at one employer and a 403(b) at another, tracking the combined total is your responsibility. Governmental 457(b) plans have a separate limit that doesn’t count against the $24,500.
2026 Limits You Cannot Exceed
Every calculation runs into these federal ceilings:
- Base elective deferral: $24,500, covering traditional and Roth deferrals combined.
- Age-50 catch-up: an additional $8,000 if you turn 50 or older by December 31, 2026.
- Ages 60–63 super catch-up: an additional $11,250 instead of the $8,000 age-50 amount, if you turn 60, 61, 62, or 63 during 2026.
- 15-year service catch-up: up to $3,000 extra per year, with a $15,000 lifetime cap, for long-tenured employees at qualifying organizations.
- Total annual additions under Section 415(c): $72,000, covering deferrals, employer contributions, and forfeitures. Catch-ups sit on top of this ceiling.
The $24,500 base and the $8,000 age-50 catch-up come from the IRS’s 2026 cost-of-living announcement, which applies to 401(k) and governmental 457 plans as well.2Internal Revenue Service. 401(k) Limit Increases to $24,500 for 2026, IRA Limit Increases to $7,500 The super catch-up for ages 60–63 was introduced by SECURE 2.0 and confirmed on the IRS 403(b) contribution limits page.3Internal Revenue Service. Retirement Topics – 403(b) Contribution Limits The $72,000 total annual addition ceiling comes from the IRS cost-of-living tables.4Internal Revenue Service. COLA Increases for Dollar Limitations on Benefits and Contributions
Adding Catch-Up Contributions If You Qualify
403(b) plans offer more catch-up options than any other employer-sponsored retirement plan. Knowing which ones apply to you changes the ceiling on your calculation.
Age-Based Catch-Up
If you’re at least 50 by the end of 2026, you can defer an extra $8,000 beyond the $24,500 base, for a total of $32,500.2Internal Revenue Service. 401(k) Limit Increases to $24,500 for 2026, IRA Limit Increases to $7,500 If you turn 60, 61, 62, or 63 during the year, the catch-up jumps to $11,250, bringing the maximum to $35,750.3Internal Revenue Service. Retirement Topics – 403(b) Contribution Limits Once you reach 64, the catch-up drops back to $8,000.
15-Year Service Catch-Up
This one is specific to 403(b) plans. If you’ve worked at the same qualifying employer for at least 15 years, you can add up to $3,000 per year, capped at $15,000 over your lifetime.5Cornell Law Institute. 26 USC 402 – Taxability of Beneficiary of Employees’ Trust The amount available in any given year also depends on a formula comparing $5,000 times your years of service against total employer contributions made on your behalf in prior years, so $3,000 is a ceiling rather than a guarantee.
How the Catch-Ups Stack
If you qualify for both the 15-year service catch-up and an age-based catch-up, the IRS requires you to use the 15-year catch-up first, with any additional room coming from the age-based amount.6Internal Revenue Service. 403(b) Plan Fix-It Guide – 15 Years of Service Catch-Up Contribution Someone who is 62 with 20 years at the same employer and hasn’t used any of the 15-year allowance could potentially defer $24,500 plus $3,000 (15-year) plus $11,250 (super catch-up), for $38,750 in a single year.
Splitting Between Traditional and Roth
Most 403(b) plans now offer both a traditional (pre-tax) option and a Roth (after-tax) option. The $24,500 limit applies to the combined total. You don’t get $24,500 in each.3Internal Revenue Service. Retirement Topics – 403(b) Contribution Limits
Traditional deferrals come out of your paycheck before income tax, lowering your taxable income now; you pay tax later when you withdraw in retirement. Roth deferrals are taxed today, but qualified withdrawals in retirement, including all growth, come out tax-free. A withdrawal qualifies if it happens at least five years after your first Roth contribution and you’re at least 59½, disabled, or deceased.
The choice affects your take-home pay, not the amount going into the account. If you defer $250 per paycheck traditional, your taxable wages drop by $250 that period. If you defer the same $250 Roth, your taxable wages don’t change and you’ll see a larger tax withholding line. Many people split between the two accounts to hedge against uncertainty about future tax rates.
Higher Earners: The Roth Catch-Up Rule
Starting in 2026, SECURE 2.0 requires that if your prior-year FICA wages from the employer sponsoring the plan exceeded $145,000 (indexed for inflation), any catch-up contributions must go into a Roth account rather than traditional pre-tax.7Internal Revenue Service. Treasury, IRS Issue Final Regulations on New Roth Catch-Up Rule, Other SECURE 2.0 Act Provisions The IRS granted a two-year transition period that ended December 31, 2025, so the rule is now fully in effect.
If you earned above that threshold in 2025, your 2026 catch-up deferrals will appear on your paycheck as after-tax deductions, and you’ll owe income tax on them now. If your plan doesn’t offer a Roth option, you can’t make catch-up contributions at all. Raise this with your benefits administrator before setting your 2026 deferral rate.
Adding Employer Matching
Many 403(b) plans include employer matching. The formulas vary, but a common one is a 50% match on the first 6% of salary you defer. On $60,000, you contribute $3,600 (6% of $60,000) and your employer adds $1,800 (50% of $3,600). Monthly, that’s an extra $150 in your account at no cost to you.
To figure out matching for your specific plan, pull two numbers from your Summary Plan Description or benefits portal: the match percentage and the match ceiling (the maximum percentage of your salary that qualifies for the match). Multiply your gross salary by the ceiling, then multiply the result by the match rate. A dollar-for-dollar match up to 4% on the same $60,000 salary yields $2,400 in employer money. Contributing less than the amount needed to capture the full match is guaranteed money left behind.
Vesting Schedules
Your own deferrals belong to you from day one. Employer contributions may not. Most plans impose a vesting schedule that determines how much of the employer money you keep if you leave before a certain number of years. Cliff vesting moves you from 0% to 100% ownership after a set period (up to three years under federal rules). Graded vesting increases ownership gradually over up to six years. Some plans, particularly safe harbor arrangements, vest employer contributions immediately. Check your plan document, because the vesting schedule affects how much of the match you’d actually walk away with if you changed jobs.
Checking the Total Annual Addition Cap
Once you’ve added your deferrals and employer contributions, compare the sum against the Section 415(c) ceiling. For 2026, total annual additions cannot exceed the lesser of $72,000 or 100% of your includible compensation. Annual additions include your elective deferrals, employer matching, employer non-elective contributions, and forfeitures allocated to you. Catch-up contributions are excluded from this count.8Internal Revenue Service. Fixing Common Plan Mistakes – Failure to Limit Contributions for a Participant
The $6,000 personal deferral plus $1,800 employer match in the earlier example totals $7,800, far below the $72,000 cap. The 415(c) limit mostly matters for high earners at organizations that make large non-elective employer contributions, such as physicians at university hospitals. A moderate salary with a standard match won’t come close.
If You Contribute Too Much
Exceeding the $24,500 elective deferral limit triggers a correction process with tax consequences. Contact your plan administrator and request a distribution of the excess plus any earnings on it by the due date of your tax return for that year, typically April 15.9Internal Revenue Service. Consequences to a Participant Who Makes Excess Annual Salary Deferrals
Missing that deadline is expensive. The excess gets taxed in the year you contributed it and taxed again when it’s eventually distributed from the plan. You don’t receive cost basis in the excess, so nothing offsets the double taxation later.9Internal Revenue Service. Consequences to a Participant Who Makes Excess Annual Salary Deferrals This is easiest to trip into when you participate in both a 403(b) and a 401(k) at different employers, since neither payroll system knows what the other is withholding. Run the combined total yourself each pay period as the year progresses.