It is an additional 10% federal tax on most 401(k) distributions taken before age 59½, on top of ordinary income tax. The penalty does not apply to plan loans or to certain exceptions such as disability, qualified medical expenses, or substantially equal periodic payments.

The amount is taxable as ordinary income at your marginal rate, plus 10% for the early-withdrawal penalty unless an exception applies. For example, a $10,000 withdrawal at a 22% marginal rate loses about $2,200 to income tax and $1,000 to the penalty, leaving roughly $6,800 before state tax.

Yes, if you separate from service during or after the calendar year you turn 55, distributions from that employer's plan are generally exempt from the 10% penalty — though they remain taxable as ordinary income.

A plan loan is not a taxable distribution if repaid on schedule, but it must be repaid with interest and becomes taxable (plus the 10% penalty if you are under 59½) if you leave the job and cannot repay it. Compare the costs carefully.

No. The calculator projects gross account growth and retirement withdrawals and does not model income tax, the 10% early-withdrawal penalty, or RMDs. Use the early-withdrawal section above as a planning guide before taking money out.

Growth mode uses a simple yearly loop. It starts with your opening balance, applies the expected return for that year, then adds your employee contribution and any match before moving to the next age. That means the calculator compounds the account once per year rather than pretending the balance grows all at once at retirement.

The calculator treats the match as a percent of your salary that is eligible for matching. If your plan matches 50% of contributions up to 6% of salary, the calculator only counts 6% of salary as match-eligible even if you contribute more than that. That keeps the estimate simple while still matching how many common plans work.

Many plans only match a slice of salary, not every dollar you contribute. The salary cap input lets the calculator model that common rule without adding a separate plan picker or vesting workflow. If your plan works differently, you can adjust the cap to fit the rule you know.

Yes. You can enter a manual starting balance and the retirement age you want to test, then the withdrawal table will project forward to age 100 or depletion. If you already ran growth mode, the withdrawal mode can also reuse the projected retirement balance and age as a starting point.

No. It is an estimate only and does not model income taxes, early withdrawal penalties, RMDs, or plan-specific rules. The calculator is meant to show gross balance movement so you can compare scenarios quickly before moving to a tax-aware planner.

Use a return rate that matches your own planning assumption instead of a single market year. Many people test a conservative rate and a more optimistic rate to see how sensitive the balance is. Because the model compounds every year, small changes in the return assumption can make a big difference over long horizons.

Different calculators may use monthly compounding, wage growth, vesting schedules, fee assumptions, or different match rules. This version stays intentionally transparent and simple so you can see the core math without hidden plan logic. The tradeoff is that the result is an estimate, not a full recordkeeper simulation.