Do 457 Contributions Reduce AGI? Pre-Tax, Roth, and Catch-Ups

Pre-tax contributions to a 457(b) plan reduce your adjusted gross income dollar for dollar; Roth 457(b) contributions do not. That single split answers the question of whether 457 contributions reduce AGI, and it drives every other tax consequence of the plan.

If you defer $24,500 into a traditional 457(b) in 2026, your W-2 will show $24,500 less in taxable wages, and your AGI drops by that same amount. If you route the same money into a designated Roth 457(b) instead, the wages stay in Box 1 and your AGI is unchanged.

How the Pre-Tax Deferral Lowers Your AGI

When you elect a traditional pre-tax 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 instead in Box 12 under Code G, which tells the IRS the money went into a 457(b) account rather than to you.¹ Because the deferral is excluded from gross income at the source, it automatically reduces your AGI without any separate deduction or adjustment line on your return.

This is different from a traditional IRA deduction. With an IRA, the income lands on your W-2 first and you claim an adjustment on your 1040. With a 457(b) pre-tax deferral, the income never gets there. The end result is the same lower AGI, but you don’t need to itemize or pass any deduction eligibility test to get the benefit.

Why Roth 457(b) Contributions Don’t Change AGI

Designated Roth contributions to a governmental 457(b) plan are included in your taxable wages for the year you earn them. You pay full federal income tax on the money before it enters the account. Your employer reports these contributions in Box 12 of your W-2 using Code EE.¹ The wages are already in Box 1, so Roth deferrals have zero effect on your current AGI.

The tradeoff shows up in retirement. Qualified withdrawals from a Roth 457(b), including all the investment growth, come out completely tax-free.² Choosing Roth means you’re trading an AGI reduction today for tax-free income later.

How Much AGI You Can Shave Off in 2026

The ceiling on your AGI reduction is the IRS elective deferral limit, which adjusts annually for inflation. For 2026, the standard limit is $24,500.³ A participant who defers the full $24,500 on a pre-tax basis excludes that entire amount from their AGI for the year.

Several catch-up provisions raise that ceiling.

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 $32,500.³ Deferred pre-tax, the extra $8,000 reduces AGI on the same terms as the base amount.

Enhanced Catch-Up for Ages 60 Through 63

Beginning with the 2025 tax year, 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, the enhanced catch-up is $11,250, and it replaces rather than adds to the standard age 50 catch-up.³ Total possible pre-tax deferral in that age window is $35,750.

Special Three-Year Catch-Up

The 457(b) plan has a catch-up rule that no other retirement plan offers. During the three tax years immediately 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.⁴ For 2026, twice the standard limit is $49,000.

You cannot use the special three-year catch-up and any age-based catch-up in the same tax year. You pick whichever one produces the larger contribution.⁴

Stacking a 457(b) With a 403(b) or 401(k)

The 457(b) contribution limit is completely independent of the limit that applies to 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 deferral of $49,000.⁵ That’s nearly double the AGI reduction available to someone with only a 401(k).

The catch-up provisions stack independently too. A 55-year-old government employee with access to both plans could defer $32,500 into the 457(b) and $32,500 into the 403(b), for $65,000 in total pre-tax deferrals and the same amount shaved off AGI.

What the Deferral Doesn’t Reduce: FICA

Pre-tax 457(b) deferrals reduce your income for federal (and usually state) income tax purposes. They do not reduce your wages for Social Security and Medicare. The IRS treats amounts deferred under a 457(b) plan as FICA-taxable wages at the time the services are performed or when the amounts vest, whichever is later.⁶

Vesting is immediate for most government employees, so the full salary, including the amount 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 is the same whether you contribute or not.

What a Lower AGI Actually Buys You

AGI, or modified AGI that starts with AGI, is the gatekeeper for dozens of tax provisions. A pre-tax 457(b) deferral doesn’t just save you the marginal tax rate on the deferred amount. It can also change your position on income-tested benefits and surtaxes.

Many credits and deductions phase out as income rises. The Child Tax Credit, the Lifetime Learning Credit, and the student loan interest deduction all use AGI-based thresholds, so a lower AGI can keep you inside the eligibility window or increase the amount you receive.
Medicare Part B and Part D premiums include income-related monthly adjustment amounts that kick in at specific modified AGI thresholds. Staying below those thresholds can save hundreds or thousands of dollars a year in premium surcharges.
The 3.8% Net Investment Income Tax applies when modified AGI exceeds $200,000 for single filers or $250,000 for married couples filing jointly. Pre-tax deferrals can push MAGI below those lines and eliminate the surtax on investment income.⁷
FAFSA calculations rely heavily on parental income, so a lower AGI can improve need-based financial aid eligibility for college-bound children.

Where the AGI Rule Doesn’t Apply

The pre-tax AGI mechanic above is written around governmental 457(b) plans. Two related arrangements behave differently and are worth flagging so you don’t assume they work the same way.

Non-governmental 457(b) plans, offered by tax-exempt organizations such as hospitals and charities, still exclude pre-tax deferrals from current-year AGI. The structural difference sits elsewhere: the assets legally remain the property of the employer, sit in a trust available to the employer’s general creditors, and cannot be rolled into an IRA or 401(k). Non-governmental 457(b) plans also cannot offer Roth contributions and are generally limited to a smaller group of highly compensated employees.⁸

A 457(f) plan is a different arrangement entirely, used by tax-exempt organizations for supplemental executive benefits. 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 become fully vested.⁹ That income hits your AGI when the forfeiture risk ends, whether or not you’ve received any cash. A 457(f) is not a tool for reducing AGI in the year you defer.

1
Internal Revenue Service. General Instructions for Forms W-2 and W-3 (2026)
2
Internal Revenue Service. Retirement Plans FAQs on Designated Roth Accounts
3
Internal Revenue Service. 401(k) Limit Increases to $24,500 for 2026, IRA Limit Increases to $7,500
4
Internal Revenue Service. Issue Snapshot – Section 457(b) Plan of Governmental and Tax-Exempt Employers – Catch-Up Contributions
5
Internal Revenue Service. Retirement Topics – 457(b) Contribution Limits
6
Internal Revenue Service. Employer Contributions to 457(b) Plans
7
Internal Revenue Service. Topic No. 559, Net Investment Income Tax
8
Fidelity. What Is a 457(b) Plan
9
Office of the Law Revision Counsel. 26 USC 457 – Deferred Compensation Plans of State and Local Governments and Tax-Exempt Organizations