Deciding whether to borrow from a 401k or a bank comes down to a trade-off between cost today and risk tomorrow. A 401k loan is cheaper, faster, and ignores your credit score, but it exposes you to a surprise tax bill if you leave your job and quietly drains years of investment growth from your retirement account. A bank personal loan costs more in interest and depends on your credit, yet the terms don’t change if your job does, and your retirement savings keep compounding untouched.
Which One Is Actually Cheaper
On the sticker price, the 401k wins. Plan administrators typically set the rate at the prime rate plus one percentage point, which in early 2026 puts most 401k loans between 8.5% and 9.5%. Personal loan rates depend on your credit: borrowers with excellent credit might land near 8%, while those with fair or poor credit can see 20% or higher, up to roughly 36%. Many bank and online lenders also take an origination fee of 1% to 10% out of the proceeds, so a $10,000 personal loan can arrive as $9,000 in your account. 401k loans rarely carry origination fees, though some plans add a small administrative charge.
The interest you pay on a 401k loan goes back into your own account instead of to a lender, which sounds like free money. It isn’t. Two hidden costs flip the math.
The Double-Taxation Catch on 401k Interest
With a traditional pre-tax 401k, your original contributions went in before taxes. When you repay a loan, though, both principal and interest come out of your take-home pay, which has already been taxed. That interest then sits in the account and gets taxed again as ordinary income when you withdraw it in retirement. On a $50,000 loan at 9% over five years, that’s roughly $12,000 of interest exposed to tax twice.
Personal loan interest is a one-time expense. The IRS classifies it as personal interest, the same category as credit card debt, so it isn’t deductible for most borrowers.1Internal Revenue Service. Topic No. 505, Interest Expense But once you pay it, it’s gone. There’s no second tax event waiting for you decades later.
What You Have to Qualify For
A bank loan opens up your financial life. Lenders pull a hard credit inquiry, usually looking at a FICO Score 8, and most want to see a score in the mid-600s at minimum. They also check recent tax returns and W-2s to calculate your debt-to-income ratio, and a high ratio can shrink the approved amount or kill the application. The hard inquiry itself can nudge your score down temporarily.
A 401k loan skips every piece of that. No credit check, no income verification, no debt-to-income math, and nothing reported to the credit bureaus. The loan is invisible to the credit system, which protects your score but also means you build no credit history by paying it back.
The limits come from different places. For a 401k loan, federal law caps the amount at the lesser of $50,000 or 50% of your vested account balance.2Internal Revenue Service. Retirement Plans FAQs Regarding Loans If 50% of your vested balance is under $10,000, your plan may let you borrow up to $10,000, but plans aren’t required to offer that exception.3Internal Revenue Service. Retirement Topics – Loans The $50,000 cap also drops if you’ve had another 401k loan in the past 12 months; the limit is reduced by the highest balance during that period.
A few other 401k boundaries worth knowing before you count on this option:
- Not every plan allows loans. Employers aren’t required to offer the feature. Check your summary plan description or call the administrator first.
- You can only borrow from a plan at your current employer. Old 401ks at former employers are off the table.3Internal Revenue Service. Retirement Topics – Loans
- If your plan provides a qualified joint and survivor annuity, your spouse may have to consent in writing, within 90 days before the loan is secured against your account.4Internal Revenue Service. Issue Snapshot – Spousal Consent Period to Use an Accrued Benefit as Security for Loans
What Happens If You Leave Your Job
This is the risk that makes 401k loans genuinely dangerous, and it’s the single biggest reason to think twice. If you quit, get laid off, or are fired with an unpaid balance, the plan administrator typically treats the remaining loan as a plan loan offset. You then have until the federal tax filing deadline, including extensions, for the year the offset occurs to roll that amount into an IRA or another eligible retirement plan.3Internal Revenue Service. Retirement Topics – Loans Miss that deadline, and the entire outstanding balance becomes a taxable distribution.
The practical problem: if you borrowed $30,000 and still owe $25,000 the day you leave, you need $25,000 in cash from somewhere else to complete the rollover. Most people who just lost a job don’t have that liquidity sitting around, which is how a cheap loan turns into an expensive tax event.
A bank loan is immune to all of this. The payment, rate, and term stay the same no matter where your paycheck comes from. If your employment situation is at all uncertain, that stability is worth real money.
What Happens If You Can’t Pay
Default looks very different on the two loans.
On a 401k loan, missing payments (loans must generally be repaid in substantially level installments at least quarterly) can cause the whole balance to be reclassified as a deemed distribution.5Internal Revenue Service. Fixing Common Plan Mistakes – Plan Loan Failures and Deemed Distributions The plan reports it on Form 1099-R to you and the IRS.6Internal Revenue Service. 2025 Instructions for Forms 1099-R and 5498 The unpaid amount gets added to your taxable income at your ordinary rate, which for 2026 ranges from 10% to 37%.7Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026 If you’re under 59½, the IRS tacks on a 10% early distribution penalty.8Internal Revenue Service. Retirement Topics – Exceptions to Tax on Early Distributions A $20,000 default triggers $2,000 in penalty alone, plus roughly $4,400 in federal income tax for someone in the 22% bracket, before any state tax.
Default on a bank loan has no tax consequences. The damage is credit damage: late payments get reported, and collections entries can stay on your report for seven years. The lender may eventually sue or try to garnish wages. That’s painful, but it doesn’t generate a tax bill on money you’ve already spent.
Repayment windows differ as well. Personal loans typically run two to seven years at a fixed monthly payment. 401k loans have a federal maximum of five years, except when the loan is used to buy your primary residence, which can extend beyond that.3Internal Revenue Service. Retirement Topics – Loans Most 401k plans collect through automatic payroll deductions.
The Cost You Won’t See on the Statement
When you take a 401k loan, your plan sells the corresponding investments to fund it. Those dollars stop earning returns, stop collecting dividends, and stop compounding until you pay them back. If the market gains more than your loan rate during the repayment term, you lose the difference. And because retirement savings compound, five years of missed growth on a $20,000 loan at age 35 isn’t just a five-year gap. It’s the compounding those returns would have produced over the next 30 years.
A bank loan leaves your retirement account alone. Whatever the market does during repayment, your 401k is still in it. That’s the real trade: a lower interest rate now versus potentially larger retirement savings later.
When to Choose Each One
A 401k loan tends to be the better move when:
- The amount is small compared to your total vested balance.
- Your job feels stable for the full repayment term.
- Your credit score would push a bank loan into high-interest territory.
- You can realistically repay quickly, limiting time out of the market.
A bank loan tends to be the better move when:
- You might change jobs, voluntarily or not, in the next few years.
- You want to build or maintain credit history.
- Your retirement balance is small enough that pulling money out would meaningfully hurt long-term growth.
- You need more than your plan’s borrowing limit, or your plan doesn’t offer loans at all.
Weigh the downside scenarios honestly. The worst case on a bank loan is damaged credit and possible collections. The worst case on a 401k loan is an unexpected tax bill, a 10% early-withdrawal penalty, and permanently smaller retirement savings. The 401k monthly payment often feels easier, but for many borrowers the hidden downside is the larger financial threat.