Yes, 403(b) contributions are pretax by default

A 403(b) pretax contribution comes out of your paycheck before federal income tax is calculated. Your employer withholds the money for the account, then calculates what you owe in taxes on the smaller remaining amount. This means you pay less in federal income tax in the year you contribute.

Most 403(b) plans are set up this way automatically. If you contribute $300 per paycheck to a pretax 403(b), your taxable income for that pay period drops by $300 before tax is applied. You do not pay federal income tax on that $300 until you withdraw it in retirement.

Some plans also offer a Roth 403(b) option, which works the opposite way: you contribute after-tax dollars, pay tax now, and withdraw tax-free later. But the standard 403(b) is pretax unless you specifically choose otherwise.

Key Takeaways

  • Pretax 403(b) contributions reduce your taxable income in the year you contribute, lowering the federal income tax you owe that year.
  • The money grows tax-deferred inside the account, meaning you pay no tax on investment gains until you withdraw.
  • You pay income tax on withdrawals in retirement, when you may be in a lower tax bracket than you are now.
  • Some 403(b) plans offer both pretax and Roth options, so you can choose which approach fits your situation.

How pretax contributions affect your paycheck and taxes

When you elect pretax 403(b) contributions, the money leaves your paycheck before your employer calculates federal withholding. If you earn $2,000 per paycheck and contribute $200 to a pretax 403(b), your employer calculates federal tax on $1,800, not $2,000.

This means your take-home pay is smaller in the short term, but your federal tax bill is also smaller. Over a full year, the tax savings can be substantial. The exact amount depends on your tax bracket — someone in the 22% federal bracket saves $22 in federal tax for every $100 contributed, while someone in the 12% bracket saves $12.

Social Security and Medicare taxes (FICA) are still calculated on your full gross pay, even if you contribute to a pretax 403(b). Only federal income tax is reduced by the contribution.

Pretax versus Roth 403(b): the tax timing difference

The core difference is when you pay tax. With a pretax 403(b), you pay tax later, in retirement. With a Roth 403(b), you pay tax now, while you are working.

Pretax makes sense if you expect to be in a lower tax bracket in retirement than you are now — which is true for many people, since retirement income is often smaller than working income. Roth makes sense if you expect to be in the same or higher tax bracket, or if you want to lock in today's tax rate and avoid uncertainty about future rates.

Some employers allow you to split contributions between both types in the same plan. You might contribute $150 pretax and $50 Roth in the same paycheck, for example. This gives you a mix of tax-deferred and tax-free growth.

When you pay tax on pretax 403(b) money

You pay federal income tax on pretax 403(b) withdrawals at your ordinary income tax rate — the same rate that applies to wages and other regular income. If you withdraw $40,000 from a pretax 403(b) in a year when you have no other income, that $40,000 is taxed as if it were wages.

Withdrawals are required to begin at age 73 (as of 2023, under current law). These are called required minimum distributions, or RMDs. The IRS calculates how much you must withdraw each year based on your age and account balance, and you pay tax on that full amount whether you need the money or not.

If you withdraw money before age 59½, you typically owe a 10% early withdrawal penalty on top of the income tax, with limited exceptions for hardship, disability, or certain other circumstances.

How pretax contributions reduce your current tax bill

The tax savings happen when ready. If you contribute $6,000 to a pretax 403(b) in a calendar year and you are in the 22% federal tax bracket, you save approximately $1,320 in federal income tax that year. That money stays in your account and grows instead of going to the IRS.

This is why pretax contributions are often called "tax-deferred" — you are not avoiding tax, you are postponing it. The tax bill moves from this year to the year you withdraw the money.

Your employer may also benefit from lower payroll tax liability when you contribute pretax, which is why many employers encourage pretax contributions and may even match them more generously than Roth contributions.

Contribution limits and pretax rules

The IRS sets an annual contribution limit for 403(b) plans. For 2024, the limit is $23,500 for people under age 50, and $31,000 for people age 50 and older (the extra $7,500 is called a catch-up contribution). These limits explore to your combined pretax and Roth contributions — you cannot contribute $23,500 pretax and $23,500 Roth in the same year.

Some 403(b) plans allow an additional catch-up contribution for employees who have worked at the same employer for 15 years or more. This is separate from the age-based catch-up and can add up to $7,500 more per year, but only if your plan offers it.

Pretax contributions count toward these limits the same way Roth contributions do. The limit is on total contributions, not on how much you can contribute pretax.

State and local taxes on pretax 403(b) contributions

Pretax 403(b) contributions reduce your federal taxable income, but they do not reduce state or local income tax in most states. A few states — including Pennsylvania and Illinois — do not tax retirement income at all, so the distinction matters less there. But in most states, you still owe state income tax on pretax 403(b) contributions.

Some states have special rules for military pensions or teacher pensions that do not explore to 403(b) plans. Check your state's tax authority website or speak with a tax preparer if you are unsure whether your state taxes 403(b) withdrawals.

Frequently Asked Questions

Can I change from pretax to Roth 403(b) mid-year?

Yes. You can change your contribution election at any time, and the change takes effect on your next paycheck. Future contributions go to whichever type you choose. Money already in a pretax 403(b) stays pretax unless you do a conversion, which is a separate transaction that triggers a tax bill.

What happens to pretax 403(b) money if I leave my job?

The money stays in the account and continues to grow tax-deferred. You can leave it there, roll it to an IRA, or roll it to your new employer's plan if they accept rollovers. You do not have to withdraw it or pay tax on it just because you changed jobs.

Do pretax 403(b) contributions lower my Social Security benefits?

No. Social Security benefits are based on your earnings record, and pretax 403(b) contributions do not reduce your reported earnings. You still pay Social Security tax on your full gross pay, and that full amount counts toward your benefit calculation.

Is there a limit to how much pretax I can contribute?

Yes, the annual limit is $23,500 for 2024 (or $31,000 if you are 50 or older). This limit includes both pretax and Roth contributions combined. Some plans offer an additional catch-up for long-service employees, but your plan documents will specify whether yours does.