The 30-second answer
A 401(k) loan and a HELOC have similar headline rates in 2026 — roughly 8.25% for the 401(k) loan (Prime + 1%) and 7.0%-9.5% for a HELOC. What kills the 401(k) loan on total-cost analysis is opportunity cost: every dollar you borrow from your 401(k) stops growing in the market. Historically, that's about a 10% annual return you give up. Add job-loss risk (immediate taxable-event trigger if you separate from the employer) and the double taxation of the interest, and the HELOC wins for most homeowners with equity.
The headline rate comparison
| Product | Stated APR (2026) | Max borrow | Term |
|---|---|---|---|
| 401(k) loan | Prime + 1% = ~8.25% | Lesser of 50% of vested balance or $50,000 | 5 years (30 for home purchase) |
| HELOC | 7.0% - 9.5% | Typically 85% CLTV of home value | 10-year draw + 20-year repayment (typical) |
On stated rate, they're roughly comparable for a well-qualified borrower. The story changes fast once you count what the 401(k) loan actually costs you beyond the stated rate.
Hidden cost #1: opportunity cost on the borrowed balance
When you take a $50,000 loan from your 401(k), that $50,000 leaves the market. You're no longer earning market returns on it — you're earning whatever interest rate you're paying yourself, which by definition equals your loan cost, not the market's return.
Over the last 30 years the S&P 500 has averaged about 10% annualized returns. If you borrow $50,000 from your 401(k) for a 5-year loan and the market returns 10% during that period, here's the opportunity cost:
| Scenario | Balance after 5 years |
|---|---|
| Left in 401(k) at 10% return | $80,526 |
| Borrowed at 8.25%, repaid on schedule (interest returned to 401(k)) | ~$61,000 |
| Foregone growth | ~$19,500 |
You "paid yourself back" the $50,000 plus interest, but you're roughly $19,500 poorer at retirement than if you'd left the money invested and borrowed elsewhere. That's real money the HELOC comparison must factor in.
Counterargument: markets don't return 10% every year, and if the market drops during your loan term, the opportunity cost is smaller or even negative. That's true. But you don't know in advance which environment you're in, and the long-term historical case favors staying invested.
Hidden cost #2: the job-loss trigger
This is the single most important asymmetry between these two products and the one most 401(k) borrowers don't fully weigh until it's too late.
If you leave your employer — voluntarily or not — with an outstanding 401(k) loan balance, current rules give you until the tax filing deadline of the year after separation to repay the balance in full. If you can't (and if you've just been laid off, you probably can't), the outstanding balance is treated as an early withdrawal:
- The full unpaid balance is added to your ordinary income for that tax year.
- If you're under age 59½, add a 10% early-withdrawal penalty on top.
- The combined federal + state + penalty hit is often 35-45% of the loan balance.
On a $50,000 loan balance, that's potentially $17,500-$22,500 in taxes and penalties — on top of already having lost your job. There is no equivalent trigger on a HELOC. If you lose your job with a HELOC balance, you still owe the balance and still make monthly payments (or negotiate hardship options), but the entire outstanding amount doesn't become suddenly, immediately, taxably due.
Hidden cost #3: the double-taxation problem on interest
The pitch on 401(k) loans is "you pay interest to yourself." Technically true. Practically, that interest is subject to a subtle double-taxation problem that people don't notice at the time.
Here's the mechanic: You repay the 401(k) loan (principal + interest) with after-tax dollars from your paycheck. That interest sits in the 401(k) as ordinary retirement money. When you eventually withdraw it in retirement, it's taxed again as ordinary income.
In effect, you're paying interest with post-tax dollars, then having those dollars taxed a second time on withdrawal. The principal doesn't have this problem (it was already yours), but the interest portion does. Over a 5-year, $50,000 loan at 8.25%, the interest you'd repay is roughly $11,000 — and every dollar of that is subject to the double-tax treatment.
Where the 401(k) loan actually wins
The 401(k) loan isn't universally bad. Three scenarios where it's genuinely the right call:
You don't own a home, or lack equity. If a HELOC isn't available to you, the 401(k) loan often beats personal loans, credit cards, or high-interest signature debt on cost. It's a real option when other secured borrowing isn't.
The loan is small and short-term. If you're borrowing $8,000 for six months to bridge a known cash gap, opportunity cost is limited (you were out of the market for six months) and job-loss risk within that window is usually manageable. The 401(k) loan's simplicity and speed can win here.
Your 401(k) sits in low-return assets. If your account is 90% money-market or short-duration bonds returning 4%, the opportunity cost is small. Borrowing at 8.25% against 4% returning assets is a much different calculation than against 10% equity returns.
You're near retirement with no market-return exposure. If you're 62 and holding mostly conservative allocations, opportunity cost is limited and the job-loss trigger is less catastrophic because you're near 59½ anyway.
The clean framework for choosing
- Do you own a home with equity? If no, the 401(k) loan probably beats other unsecured options. If yes, keep going.
- Is your job stable for the next 5 years? If unsure, the 401(k) loan's separation-trigger risk is disqualifying. Take the HELOC.
- Is your 401(k) invested for growth (target-date fund, stock-heavy allocation)? If yes, opportunity cost is real. HELOC wins.
- Is the loan short-term (under 12 months) and small (under $10K)? If yes, the 401(k) loan's opportunity cost is limited. Either works.
For a typical homeowner in their 40s with equity, a growth-invested 401(k), and normal job risk, the HELOC wins this comparison more often than the retail personal-finance world admits.
The lender's honest take
The 401(k) loan gets sold as "cheap" because the stated rate is low and "you pay yourself back." Both of those are true only on the narrowest reading. Once you count opportunity cost on the borrowed balance, the job-loss trigger, and the double-taxation of interest, the true all-in cost typically exceeds the HELOC's cost meaningfully.
The one place I do encourage borrowers to consider a 401(k) loan is when they don't have home equity and their alternative is a 15-20% personal loan or a credit card. In that comparison, the 401(k) loan's problems are smaller than the alternative's.
Compare a real HELOC rate before pulling from retirement
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FAQ
Is a 401(k) loan cheaper than a HELOC?
On stated interest rate, sometimes. On true all-in cost including opportunity cost, job-loss risk, and double taxation of interest, usually not.
What happens to a 401(k) loan if I lose my job?
You have until the tax filing deadline of the following year to repay the balance. If you don't, it's treated as a taxable early distribution — ordinary income tax plus a 10% penalty if you're under 59½.
Is 401(k) loan interest paid to yourself?
Yes, but that interest is paid with after-tax dollars and taxed again on withdrawal — the double-taxation problem.
When does a 401(k) loan actually make sense?
When you don't have home equity, when the loan is small and short-term, when your 401(k) is in low-return assets, or when you're near retirement with limited growth exposure.
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