Yes — pre-tax contributions to a 457(b) plan reduce your adjusted gross income dollar for dollar, while Roth 457(b) contributions do not. If you defer $24,500 into a traditional 457(b) in 2026, your W-2 shows $24,500 less in taxable wages and your AGI drops by that same amount. Roth contributions, by contrast, are taxed before they enter the account and leave your current-year AGI untouched.
How Pre-Tax 457(b) Deferrals Come Off Your AGI
When you elect a traditional deferral, your employer withholds the money before calculating federal income tax. The deferred amount never appears as taxable wages in Box 1 of your Form W-2; it shows up in Box 12 under Code G.1Internal Revenue Service. General Instructions for Forms W-2 and W-3 (2026) Because the deferral is excluded from gross income at the source, it automatically reduces AGI on your return. You don’t claim a separate deduction or adjustment, and you don’t have to itemize.
That’s different from a traditional IRA, where the wages hit Box 1 first and you take an above-the-line adjustment on your 1040. With a 457(b), the exclusion happens on the W-2 itself. The result is the same lower AGI, but there’s no eligibility test to clear.
Why Roth 457(b) Contributions Don’t Lower AGI
Designated Roth contributions to a governmental 457(b) are included in your taxable wages the year you earn them. You pay full federal income tax on the money before it goes into the account, and the employer reports it in Box 12 under Code EE.1Internal Revenue Service. General Instructions for Forms W-2 and W-3 (2026) The wages are already in Box 1, so Roth deferrals have zero effect on current AGI.
What you get instead is tax-free growth. A qualified Roth 457(b) distribution — contributions plus all investment earnings — comes out tax-free once you’ve reached age 59½ (or become disabled or died) and at least five tax years have passed since your first Roth contribution to that plan.2Internal Revenue Service. Retirement Plans FAQs on Designated Roth Accounts Choosing Roth is a trade: no AGI reduction today, no tax on withdrawals later.
How Much AGI You Can Shave Off in 2026
The ceiling on your pre-tax AGI reduction is set by the IRS elective deferral limit. For 2026, the standard limit is $24,500.3Internal Revenue Service. 401(k) Limit Increases to $24,500 for 2026, IRA Limit Increases to $7,500 A participant who defers the full amount pre-tax excludes that entire $24,500 from AGI.
Several catch-up provisions can push the ceiling higher.
Age 50 Catch-Up
Participants in governmental 457(b) plans who are 50 or older by year-end can contribute an additional $8,000 in 2026, for a combined limit of $32,500.3Internal Revenue Service. 401(k) Limit Increases to $24,500 for 2026, IRA Limit Increases to $7,500 If the extra $8,000 is pre-tax, it reduces AGI the same way the base deferral does.
Enhanced Catch-Up for Ages 60 Through 63
Starting in 2025, the SECURE 2.0 Act created a higher catch-up tier for participants who are 60, 61, 62, or 63 during the calendar year. For 2026, that enhanced amount is $11,250, and it replaces the standard age 50 catch-up rather than stacking on top of it.3Internal Revenue Service. 401(k) Limit Increases to $24,500 for 2026, IRA Limit Increases to $7,500 Total possible deferral in that four-year window: $35,750.
Special Three-Year Catch-Up
The 457(b) also has its own catch-up rule that exists nowhere else. During the three tax years before your plan’s designated normal retirement age, you can contribute up to the lesser of twice the standard limit or your “underutilized amount” from prior years of plan eligibility.4Internal Revenue Service. Issue Snapshot – Section 457(b) Plan of Governmental and Tax-Exempt Employers – Catch-Up Contributions For 2026, twice the standard limit is $49,000. The underutilized amount is the sum of the gap between what you could have deferred and what you actually deferred in each eligible year.
You cannot use the three-year catch-up and an age-based catch-up in the same tax year; you pick whichever yields the larger contribution.4Internal Revenue Service. Issue Snapshot – Section 457(b) Plan of Governmental and Tax-Exempt Employers – Catch-Up Contributions The three-year version tends to win when you’ve had years of light contributions and are approaching normal retirement age.
Stacking a 457(b) With a 403(b) or 401(k)
This is where the AGI reduction gets unusually large. The 457(b) limit is independent of the limit for 401(k) and 403(b) plans. If your employer offers both a 457(b) and a 403(b), which is common in public education and government, you can defer $24,500 into each in 2026, for a combined pre-tax reduction of $49,000.5Internal Revenue Service. Retirement Topics – 457(b) Contribution Limits
The catch-ups stack independently too. A 55-year-old with access to both plans could defer $32,500 into the 457(b) and $32,500 into the 403(b), reaching $65,000 in pre-tax deferrals for the year. For high earners near retirement, that scale of AGI compression can change a tax bracket outright.
What Pre-Tax 457(b) Contributions Don’t Reduce
The AGI benefit is a federal (and usually state) income tax benefit only. Pre-tax 457(b) deferrals do not reduce your wages for Social Security and Medicare taxes. The IRS treats deferred amounts as FICA-taxable wages at the time services are performed or when the amounts vest, whichever is later.6Internal Revenue Service. Employer Contributions to 457(b) Plans Vesting in most government plans is immediate, so your full salary — including what you defer — is subject to the 6.2% Social Security tax (up to the wage base) and the 1.45% Medicare tax. Your FICA withholding doesn’t change whether you contribute or not.
What a Lower AGI Actually Buys You
AGI, or modified AGI (which starts with AGI), is the gatekeeper for a long list of tax provisions. Reducing it through pre-tax 457(b) contributions creates effects well beyond the direct tax savings on the deferred income.
- Credits and deductions that phase out with income, including the Child Tax Credit, the Lifetime Learning Credit, and the student loan interest deduction, use AGI-based thresholds. A lower AGI can keep you inside the window or increase the amount you qualify for.
- Medicare Part B and Part D premiums include income-related monthly adjustment amounts (IRMAA) that kick in at specific modified AGI thresholds. Staying below those thresholds can save hundreds or thousands of dollars a year in surcharges.
- The 3.8% Net Investment Income Tax applies when modified AGI exceeds $200,000 for single filers or $250,000 for joint filers. Pre-tax 457(b) deferrals can push MAGI below those lines and eliminate the surtax on investment income.7Internal Revenue Service. Topic No. 559, Net Investment Income Tax
- FAFSA calculations lean heavily on parental income, so a lower AGI can improve a college-bound child’s need-based aid eligibility.
The savings compound. A $24,500 AGI reduction isn’t just the marginal tax rate on that income; it can also restore credit eligibility, dodge an IRMAA tier, and keep the NIIT off your investment income entirely.
Where This Treatment Doesn’t Apply
Everything above describes governmental 457(b) plans sponsored by state and local governments. Two related arrangements work differently.
Non-governmental 457(b) plans, offered by tax-exempt organizations like hospitals and charities, give the same pre-tax AGI reduction on deferrals, but the plan assets legally remain employer property and sit in a trust reachable by the employer’s creditors. Balances cannot be rolled into an IRA, 401(k), or any other retirement account, and these plans generally cannot offer Roth contributions.8Fidelity. What Is a 457(b) Plan The AGI benefit is real; the money is not as portable or protected as it is in a governmental plan.
A 457(f) plan is a different animal entirely. Deferred compensation under a 457(f) is included in your gross income in the first tax year when there is no longer a substantial risk of forfeiture, typically the year you fully vest.9Office of the Law Revision Counsel. 26 USC 457 – Deferred Compensation Plans of State and Local Governments and Tax-Exempt Organizations That income hits your AGI when the forfeiture risk ends, whether or not any cash has been paid out. A 457(f) does not give you the year-to-year AGI control that a 457(b) does; the timing is set by the vesting schedule, and planning centers on preparing for the income spike in the vesting year.