401(k) and Retirement Plan Taxes: Contributions, Withdrawals, and Limits

Filing & Brackets · RETIREMENT

How 401(k)s, IRAs, SEP-IRAs, and other retirement plans are taxed — pre-tax vs. Roth contributions, employer matches, contribution limits, early-withdrawal penalties, and required minimum distributions.

Retirement accounts are the most accessible tax shelter most Americans will ever have. Whether it's a workplace 401(k), an IRA, or a small-business SEP, these plans let you defer or eliminate tax on investment growth — but the rules around contributions, employer matches, withdrawals, and penalties trip people up constantly. Understanding the tax treatment helps you keep more of what you save.

Pre-Tax vs. Roth Contributions

The biggest decision in any retirement plan is when you pay tax:

• Traditional (pre-tax): Contributions reduce your taxable income now; withdrawals in retirement are taxed as ordinary income
• Roth (after-tax): No deduction now, but qualified withdrawals — including all the growth — are completely tax-free in retirement

A common strategy: choose pre-tax when you're in a high tax bracket today, and Roth when you expect higher rates later or you're early in your career.

Contribution Limits and Employer Matches

The IRS caps annual contributions, and limits adjust for inflation. 401(k) employee deferral limits are far higher than IRA limits, and savers age 50+ can make additional 'catch-up' contributions. Employer matching contributions are essentially free money and don't count against your personal deferral limit (though they count toward a higher overall plan limit). Always contribute at least enough to capture the full employer match — declining it is leaving compensation on the table.

Early Withdrawal Penalties

Withdraw from a traditional retirement account before age 59½ and you'll generally owe income tax plus a 10% early-withdrawal penalty. There are exceptions — including certain medical expenses, a first home purchase (IRAs), disability, and qualified birth or adoption expenses. Roth contributions (but not earnings) can usually be withdrawn anytime tax- and penalty-free because you already paid tax on them.

Required Minimum Distributions (RMDs)

Traditional retirement accounts can't grow tax-deferred forever. Starting at the RMD age (currently 73 for most people), you must withdraw a minimum amount each year and pay tax on it. Missing an RMD historically carried one of the harshest penalties in the tax code. Roth IRAs are exempt from RMDs during the original owner's lifetime — a key planning advantage.

Self-Employed and Small-Business Plans

Business owners have powerful options with much higher limits than a standard IRA, including the SEP-IRA, SIMPLE IRA, and Solo 401(k). A Solo 401(k) in particular lets an owner contribute both as 'employee' and 'employer,' often allowing very large deductible contributions. These plans can dramatically cut a profitable business owner's tax bill while building retirement savings.

Frequently Asked Questions

Should I choose a traditional or Roth 401(k)?

Traditional gives you a deduction now and taxes withdrawals later; Roth gives no deduction now but tax-free withdrawals. Roth often wins if you expect to be in the same or higher tax bracket in retirement.

Does my employer's match count toward my contribution limit?

No — employer matching does not count against your personal deferral limit, though it counts toward a higher combined plan limit. Always contribute enough to get the full match.

What's the penalty for early 401(k) withdrawal?

Generally a 10% penalty plus ordinary income tax on the amount, if you withdraw before age 59½. Several exceptions can waive the penalty.

When do I have to start taking required minimum distributions?

For most people, RMDs from traditional accounts begin at age 73. Roth IRAs have no RMDs during the original owner's lifetime.

What retirement plan is best for a self-employed person?

A SEP-IRA or Solo 401(k) usually allows much larger deductible contributions than a standard IRA. A Solo 401(k) lets you contribute as both employee and employer.