Borrowing from your 401(k) does not create an immediate tax bill, so in the ordinary case a 401(k) loan does not affect your taxes at all. The money leaves your account as a loan, not a distribution, and no income tax or 10% penalty applies as long as the loan follows the rules in Internal Revenue Code Section 72(p).1Internal Revenue Service. 401(k) Plan Fix-It Guide – Participant Loans Don’t Conform to the Requirements of the Plan Document and IRC Section 72(p) The tax problems show up later, and only in specific situations: if you default, if you leave your job with a balance owed, or if the loan quietly costs you contributions and growth you would otherwise have kept.
The Rules That Keep the Loan Tax-Free
Three conditions have to hold for the IRS to treat the money as a loan rather than a distribution.
First, the amount. You can borrow the lesser of $50,000 or half your vested balance. If half your vested balance is under $10,000, you may be allowed to borrow up to $10,000, though plans are not required to offer that floor.2Internal Revenue Service. Retirement Topics – Plan Loans The $50,000 ceiling is reduced by the highest outstanding loan balance you carried in the previous 12 months, minus what you still owe on the new loan date.3Office of the Law Revision Counsel. 26 USC 72 – Annuities; Certain Proceeds of Endowment and Life Insurance Contracts Loans from every plan sponsored by the same employer, or by related companies in a controlled group, count against one combined $50,000 cap.4Internal Revenue Service. Issue Snapshot – Borrowing Limits for Participants With Multiple Plan Loans
Second, the term. Repayment has to happen within five years.5Internal Revenue Service. Retirement Plans FAQs Regarding Loans Loans used to buy your primary residence are exempt from the five-year cap; the plan document sets the allowable term instead, often 10 to 30 years.3Office of the Law Revision Counsel. 26 USC 72 – Annuities; Certain Proceeds of Endowment and Life Insurance Contracts
Third, the schedule. Payments must be at least quarterly, in roughly equal amounts covering both principal and interest. Miss any of these three tests and the outstanding balance stops being a loan for tax purposes.
How a Default Becomes a Tax Bill
If you miss a required payment and let your plan’s grace period run out, the unpaid balance becomes a deemed distribution. The plan reports it to you and the IRS on Form 1099-R, and you owe ordinary income tax on the full outstanding amount for that year.2Internal Revenue Service. Retirement Topics – Plan Loans
If you are under 59½ when that happens, the IRS adds a 10% early distribution penalty on top of the income tax.6Internal Revenue Service. Exceptions to Tax on Early Distributions Someone in the 22% or 24% federal bracket ends up handing over 32% to 34% of the outstanding balance before any state tax. A $20,000 defaulted loan can generate a federal tax bill north of $6,000.
Leaving Your Job With a Balance Owed
Job separation with an outstanding 401(k) loan triggers a specific event called a plan loan offset. The plan cancels the loan by reducing your account balance by what you still owe, and that offset is treated as a distribution.
There is a way to avoid the tax hit. If the offset is a “qualified plan loan offset,” you have until the due date of your federal return for that year, including extensions, to roll the offset amount into an IRA or another qualified plan.7Internal Revenue Service. Plan Loan Offsets With an extension, that generally runs to about mid-October of the following year. The rollover can be funded with cash from any source, not just retirement money. Miss the deadline and the full offset amount is taxable income, plus the 10% penalty if you are under 59½.8Federal Register. Rollover Rules for Qualified Plan Loan Offset Amounts
The “Double Taxation” Claim, Honestly
You have probably heard that 401(k) loan repayments are taxed twice: you repay with after-tax dollars, then pay tax again when you withdraw in retirement. The framing is mostly wrong on the principal and correct on the interest.
On the principal, the money came out of the plan tax-free when you borrowed it. Repaying with after-tax dollars is the first time that income has ever been taxed. Withdrawing it in retirement is the second and only other time. The principal gets taxed once, same as if you had never borrowed.
The interest is different. You pay interest into your own account using after-tax dollars, and when you eventually withdraw those interest dollars in retirement, you pay ordinary income tax on them again. That portion really is taxed twice. On a $20,000 loan at 8.5% over five years, total interest runs around $4,600, so the extra tax applies to that figure, not to the whole loan.
Loan repayments, including the interest, are not tax-deductible.5Internal Revenue Service. Retirement Plans FAQs Regarding Loans
The Tax Cost You Do Not See
The quieter tax effect is what the borrowed money would have earned inside the plan. While the loan is out, that balance is not invested, so you replace market returns with the fixed rate you pay yourself. If your fund portfolio would have returned 10% and the loan charges 8.5%, you give up the difference, and that gap compounds tax-deferred for the rest of your working life. On a $25,000 loan repaid over five years, even a two-point drag translates into thousands of dollars of tax-deferred growth you no longer have at retirement.
Some plans go further and suspend new elective deferrals while a loan is outstanding. If yours does, the tax cost is direct: you lose the deduction on contributions you would have made, or the Roth tax-free growth if you contribute Roth. The 2026 elective deferral limit is $24,500, with a $7,500 catch-up at age 50 and older.9Internal Revenue Service. 401(k) Limit Increases to $24,500 for 2026; IRA Limit Increases to $7,500 Skipping even one year is difficult to make up. If your employer matches and you stop contributing, you also forfeit the match, and no interest rate you pay yourself replaces it. Your summary plan description will tell you whether contributions are suspended during a loan.
Disaster Relief
Under SECURE 2.0, plans may offer higher loan limits and longer repayment periods to participants affected by a federally declared disaster. This is optional for the plan, not automatic. If your plan has adopted it, the expanded terms can keep a loan on track and avoid the deemed distribution consequences above. Check with your plan administrator when a qualifying disaster applies to you.