401(k) Loan

Borrowing from your own 401(k) balance and repaying it with interest back to yourself — avoiding taxes and penalties as long as the loan is repaid on schedule.

A 401(k) loan lets you borrow money from your own retirement account balance and repay it — principal plus interest — back into the same account over time. Unlike a 401(k) withdrawal, a properly structured loan is not a taxable event and does not trigger the 10% early withdrawal penalty, because the money is expected to be returned. The IRS allows loans of up to 50% of your vested account balance or $50,000, whichever is less. Repayment typically happens through automatic payroll deductions over up to five years, with an exception for loans used to purchase a primary residence, which can have longer repayment terms.

The interest rate on a 401(k) loan is set by the plan — typically the prime rate plus 1–2 percentage points — and the interest you pay goes back into your own account rather than to a lender. This is frequently cited as an advantage, and it's partially true: you're not paying interest to a bank. But the real cost of a 401(k) loan is opportunity cost. The borrowed funds are not invested in the market during the repayment period. If the market returns 8% while your money is out earning 6% loan interest instead, you've lost 2 percentage points on that capital — compounded, over years, that shortfall can be significant.

The most dangerous feature of a 401(k) loan is the job-loss clause. If you leave your employer — voluntarily or through a layoff — while a 401(k) loan is outstanding, most plans require the entire remaining balance to be repaid by the tax filing deadline for that year (including extensions), typically within 60–90 days of separation. If you can't repay it, the outstanding balance is treated as a distribution: taxed as ordinary income and subject to the 10% early withdrawal penalty if you're under 59½. Losing a job and simultaneously owing taxes and penalties on thousands of dollars is a compounding financial crisis. This job-loss risk makes 401(k) loans most dangerous precisely when the person's financial situation is already under stress.

There is also a double-taxation problem that is widely misunderstood. The interest you pay on a 401(k) loan is paid with after-tax dollars — money you've already paid income tax on. When you eventually withdraw that interest in retirement, you pay income tax on it again. In contrast, the original 401(k) contributions were pre-tax and will be taxed once at withdrawal. The interest portion gets taxed twice: once when you earned and paid it, and again when you withdraw it in retirement. This isn't catastrophic on a small loan, but it's a real and often overlooked cost.

401(k) Loan vs 401(k) Withdrawal

  • Loan: no taxes or penalties at the time of borrowing; must be repaid with interest; balance is temporarily removed from investment growth.
  • Hardship withdrawal: taxed as ordinary income immediately + 10% penalty if under 59½; does not need to be repaid; permanently removes money from retirement savings.
  • In-service distribution (age 59½+): taxed as ordinary income but no penalty; no repayment required.
  • The loan is almost always preferable to a withdrawal if your only options are those two — but both should be last resorts after exhausting other sources.

The Real Costs of a 401(k) Loan

  • Opportunity cost: the borrowed amount isn't invested during the repayment period — if markets rise significantly while your money is out, you miss those gains.
  • Double taxation on interest: loan interest is paid with after-tax dollars and taxed again when withdrawn in retirement.
  • Job-loss risk: if you leave your employer with an outstanding loan, you typically have until the tax filing deadline to repay the full balance or face taxes and penalties.
  • Reduced retirement savings: even if properly repaid, the interrupted compounding leaves your retirement balance smaller than it would have been.
  • Behavioral risk: taking a 401(k) loan can normalize treating retirement savings as accessible, making future loans more likely.
  • Lost employer match on paused contributions: some employees pause their 401(k) contributions to repay the loan faster, losing employer match in the process.

When a 401(k) Loan Makes Sense (and Doesn't)

  • Potentially reasonable: short-term bridge for a home purchase down payment (longer repayment terms available), avoiding even higher-interest debt when no other options exist, a genuine short-term emergency when you have very high job security.
  • Avoid if: you're in an unstable job situation, the market is down significantly (selling low to fund the loan), you're close to retirement (less time to recover opportunity cost), or you haven't exhausted lower-risk options first.
  • Better alternatives to consider first: HYSA emergency fund, HELOC (if you own a home), personal loan at a lower rate than credit cards, hardship assistance programs, negotiating a payment plan for the underlying expense.
  • Rule of thumb: if you'd lose your job tomorrow and the outstanding loan balance would cause a financial crisis, you probably shouldn't take the loan.

Example

An employee needs $18,000 for a home down payment. Her 401(k) has $95,000 vested — she can borrow up to $47,500 (50% of balance). She takes an $18,000 loan at 7.5% (prime + 1%), repaid over 60 months via payroll deduction at roughly $360/month. The interest goes back to her account. But during those 5 years, $18,000 sits out of the market instead of compounding. If the market returns 9% annualized, she gives up roughly $3,800 in foregone growth — the real cost of the loan, beyond the structural interest payments.