Most employees are familiar with the basics of a 401(k): contribute pre-tax dollars, reduce your current taxable income, and build retirement savings on a tax-deferred basis. If your employer offers a Roth 401(k), you also have the option to contribute after-tax dollars in exchange for tax-free qualified withdrawals in retirement.
What many people don’t realize is that some 401(k) plans offer a third option: non-Roth after-tax contributions. While these contributions don’t provide the same tax advantages as Roth accounts, they can be a powerful way to increase retirement savings beyond the standard contribution limits.
Understanding Your 401(k) Contribution Options
For 2026, employees can generally contribute up to $24,500 through elective salary deferrals. Workers age 50 and older may also be eligible to make additional catch-up contributions, with limits ranging from $8,000 to $11,250, depending on age.
Traditional 401(k) Contributions
Traditional 401(k) contributions are made with pre-tax dollars, meaning:
- Contributions reduce your current taxable income
- Contributions remain subject to Social Security and Medicare (FICA) taxes
- Investments grow tax-deferred
- Withdrawals in retirement are taxed as ordinary income
Roth 401(k) Contributions
Roth contributions work differently:
- Contributions are made with after-tax dollars
- Contributions are subject to both income tax and FICA taxes
- Earnings grow tax-free
- Qualified withdrawals are tax-free, generally after age 59½ and once the account has been open for at least five years
It’s also important to note that employees whose 2025 compensation exceeded $150,000 must make any catch-up contributions to a Roth 401(k) account.
The Hidden Opportunity: After-Tax 401(k) Contributions
If your employer’s plan permits it, you may be able to make after-tax contributions to a traditional 401(k) account after you’ve reached your annual elective deferral limit.
At first glance, this may seem less attractive because these contributions:
- Are included in taxable wages
- Are subject to federal income tax
- Are subject to FICA taxes
- May also be subject to state and local income taxes
So why consider them?
The primary advantage is the ability to contribute significantly more money to your retirement account than the standard deferral limits allow.
Higher Contribution Limits Mean More Retirement Savings
While after-tax contributions don’t qualify for the annual elective deferral limit, they do count toward the overall annual contribution limit for your 401(k).
For 2026, total contributions—including:
- Employee elective deferrals (excluding catch-up contributions)
- Employer matching contributions
- After-tax employee contributions
cannot exceed the lesser of:
- $72,000, or
- 100% of your compensation
This creates an opportunity for high savers to put substantially more money into a tax-advantaged retirement account.
How Tax Basis Works
Another benefit of after-tax contributions is that they create tax basis in your account.
This means:
- The amount you contributed after tax can eventually be withdrawn tax-free.
- Any investment earnings on those contributions will still be taxable when withdrawn.
This is a key distinction from Roth accounts, where qualified withdrawals of both contributions and earnings are tax-free.
A Real-World Example
Consider the following scenario:
- Annual salary: $150,000
- Age: Under 50
- Employer match: 50%
- Plan permits after-tax contributions
You contribute the maximum $24,500 to your traditional 401(k).
Your employer contributes a matching $12,250.
This leaves room for additional contributions up to the overall annual limit:
$72,000 – $24,500 – $12,250 = $35,250
You decide to contribute $10,000 in after-tax dollars.
Here’s how the tax treatment works:
| Contribution Type | Amount | Tax Treatment |
|---|---|---|
| Traditional 401(k) Deferral | $24,500 | Excluded from federal taxable income but subject to FICA |
| Employer Match | $12,250 | Not taxable and not subject to FICA |
| After-Tax Contribution | $10,000 | Included in taxable income and subject to FICA |
The $10,000 after-tax contribution creates tax basis in the account, allowing that portion to be withdrawn tax-free in the future.
Keep Nondiscrimination Rules in Mind
401(k) plans must comply with complex IRS nondiscrimination rules designed to ensure plans don’t disproportionately benefit highly compensated employees.
While these rules generally don’t prevent employees from making after-tax contributions, plan-specific limitations may apply. It’s important to review your plan’s provisions before relying on this strategy.
Is This Strategy Right for You?
If you’re already maxing out your annual 401(k) deferrals, after-tax contributions may provide an additional opportunity to accelerate retirement savings and take advantage of tax-deferred investment growth.
Not every plan offers this feature, and the benefits depend on your overall financial picture. Reviewing your retirement goals, tax situation, and plan options can help determine whether after-tax 401(k) contributions make sense as part of your long-term strategy.
The bottom line: For high earners and dedicated savers, after-tax 401(k) contributions can be an effective way to build a larger retirement nest egg once traditional contribution limits have been reached.
