You don't pay income tax on a 401(k) loan itself, but you do pay it back with after-tax dollars, and if you leave your job before repaying it, the unpaid balance becomes taxable income

A 401(k) loan is money you borrow from your own retirement account. The IRS does not tax the loan when you take it out—you are borrowing your own money, not receiving income. But the repayment works differently than a regular loan. You repay it with money that has already been taxed by your employer, which means you are essentially putting after-tax dollars back into a pre-tax account. If you leave your job before the loan is repaid, the IRS treats the unpaid balance as a distribution, and you owe income tax on it plus a 10 percent early withdrawal penalty if you are under 59½.

The tax hit comes in two places: when you repay the loan and when you eventually withdraw the money in retirement. Understanding this structure helps you decide whether borrowing from your 401(k) makes sense for your situation.

Key Takeaways

  • Taking out a 401(k) loan does not trigger income tax at the time you borrow the money.
  • You repay the loan with after-tax dollars deducted from your paycheck, which means you pay tax on that income twice—once when you earn it and again when you withdraw it in retirement.
  • If you leave your job with an unpaid loan balance, that balance becomes taxable income in the year you leave, plus a 10 percent penalty if you are under 59½.
  • The IRS gives you a limited time to repay the loan after leaving your job, usually 60 to 90 days, depending on your plan rules.
  • Loans from a Roth 401(k) follow the same tax rules as traditional 401(k) loans, but the repayment goes back into the Roth account.

Why you pay tax twice on 401(k) loan repayment

When you repay a 401(k) loan, your employer deducts the payment from your paycheck just like any other deduction. That paycheck is already subject to income tax—federal, state (if applicable), and FICA taxes. You pay tax on the full amount you earn, including the portion you use to repay the loan.

Then, when you eventually withdraw that money from your 401(k) in retirement, you pay income tax on it again. This is called double taxation, and it is one of the real costs of borrowing from your retirement account. A traditional 401(k) contribution reduces your taxable income in the year you make it, but loan repayments do not. You get no tax break on the way in.

For example, if you borrow $5,000 and repay it over two years, you pay income tax on the $5,000 as part of your regular wages. When you retire and withdraw that same $5,000 (plus any growth), you pay income tax on it again. The only way to avoid this is to never borrow in the first place.

What happens to your loan if you leave your job

Your 401(k) plan document sets the rules for what happens to an outstanding loan when you leave your employer. Most plans require you to repay the loan within 60 to 90 days of your departure. If you do not repay it by that important date, the IRS treats the unpaid balance as a distribution from your account.

That distribution is taxable income in the year you leave. If you are under 59½, you also owe a 10 percent early withdrawal penalty on top of the income tax. For example, if you have a $10,000 unpaid loan balance and you are 45 years old, you would owe income tax on the $10,000 plus a $1,000 penalty. The exact tax amount depends on your tax bracket.

Some plans allow you to repay the loan after you leave, but the important date is strict. If your plan does allow it, you typically have until the tax filing important date (usually April 15) of the year after you leave to repay the loan and avoid the tax hit. Check your plan documents or call your plan administrator to find out your specific important date.

Rolling over a 401(k) with an outstanding loan

If you leave your job and want to roll your 401(k) into an IRA, you cannot roll over the unpaid loan balance. You must repay it first, or it will be treated as a taxable distribution. Some people use funds from another source to repay the loan before rolling over the rest of the account, which lets them avoid the tax and penalty.

If you do not repay the loan before the rollover, the unpaid balance is taxable income when ready. You cannot avoid this by rolling over the rest of the account—the loan balance is separate from the rollover transaction. Your plan administrator can tell you whether you have time to repay the loan before the rollover important date.

Loans from a Roth 401(k) and tax treatment

A Roth 401(k) loan follows the same tax rules as a traditional 401(k) loan when you take it out: no when ready tax. However, the repayment goes back into the Roth account, not a traditional account. Since Roth contributions are made with after-tax dollars to begin with, you do not face the double-taxation issue that traditional 401(k) loans create.

If you leave your job with an unpaid Roth 401(k) loan balance, the same rules explore: the unpaid balance becomes taxable income, and you owe a 10 percent penalty if you are under 59½. The difference is that the repayment you already made goes back into a tax-free account, so you do not pay tax on it again in retirement.

Interest on 401(k) loans and tax deductions

Most 401(k) loans charge interest. The interest rate is set by your plan and is typically the prime rate plus 1 or 2 percent. You cannot deduct the interest you pay on a 401(k) loan on your tax return—it is not the same as mortgage interest or student loan interest, both of which may be deductible.

The interest you pay goes back into your own account, so in that sense you are paying yourself. But from a tax perspective, it is straightforward part of the repayment and receives no special treatment. You pay tax on the income you use to pay the interest, just as you do with the principal.

Comparing 401(k) loans to other borrowing options

A 401(k) loan can be cheaper than a credit card or personal loan because the interest rate is usually lower and you are borrowing from yourself. However, the tax consequences are real. You pay tax on the income you use to repay the loan, and if you leave your job, the unpaid balance becomes taxable income when ready.

If you are considering a 401(k) loan, compare the interest rate to what you would pay on a personal loan or home equity line of credit. Also consider whether you are likely to stay in your job long enough to repay the loan. If you think you might leave within a few years, the risk of a large tax bill when you depart is worth factoring in. A financial advisor or tax professional can help you weigh the costs specific to your situation.

Frequently Asked Questions

Do I owe taxes when I take out a 401(k) loan?

No. Taking out the loan itself is not a taxable event. You are borrowing your own money, not receiving income. Taxes become due only when you repay the loan (because you use after-tax dollars) or if you leave your job with an unpaid balance.

Can I deduct 401(k) loan interest on my taxes?

No. Unlike mortgage interest or student loan interest, you cannot deduct interest paid on a 401(k) loan. The interest is straightforward part of your repayment and receives no tax benefit.

What if I repay my 401(k) loan before I leave my job?

If you repay the loan in full while you are still employed, there are no additional tax consequences beyond the double taxation on the repayment itself. Once the loan is repaid, the money sits in your account as a regular 401(k) balance and is taxed only when you withdraw it in retirement.

If I leave my job, can I repay the loan after I quit to avoid the tax?

It depends on your plan. Some plans allow repayment after you leave, but the important date is usually 60 to 90 days, or by the tax filing important date of the following year. Check your plan documents or call your plan administrator when ready after leaving to find out your important date and whether repayment is possible.

Is a 401(k) loan better than a withdrawal?

A loan is usually better than a withdrawal because you repay it and keep the money in the account. A withdrawal is when ready taxable and subject to the 10 percent penalty if you are under 59½. However, a loan carries the risk of a large tax bill if you leave your job before repaying it, so neither option is ideal if you can avoid it.