If you need to borrow cash for a major purchase, it’s tempting to pull from the two biggest pools of wealth you likely own. A HELOC to borrow from your home, or 401(k) loan to borrow from your retirement account.
On the surface, it looks like a simple math problem. Is the interest paid for a Home Equity Line of Credit (HELOC) better than the interest paid for a 401(k) loan? In the world of personal finance, the “sticker price” of interest is rarely the whole story. One of these loans involves paying interest to a bank, while the other involves “paying yourself” at the cost of your future.
Here is the breakdown of how these two options stack up over a five-year horizon assuming a $40,000 loan. The HELOC rate is set at the current average of 7.5% with the 401(k) loan at 8%.
The Contenders: HELOC vs. 401(k) Loan
1. The 401(k) Loan: Borrowing from “Future You”
A 401(k) loan is unique because you are both the lender and the borrower. You sell off $40,000 worth of your investments, and as you pay it back, the 8% interest goes directly back into your own account.
- The Pro: You aren’t losing money to a bank; you’re essentially “contributing” extra to your retirement via interest.
- The Con: That $40,000 is no longer invested. If the stock market grows by say 10% while your money is sitting out, you’ve missed out on that growth.
2. The HELOC: Borrowing Against Your Walls
A HELOC is a revolving line of credit secured by your home. At 7.5%, the rate is lower, but that interest is a pure expense paid to a lender.
- The Pro: Your retirement investments stay exactly where they are, continuing to compound and grow.
- The Con: You are putting your home on the line as collateral. If you can’t pay, you risk foreclosure.
The 5-Year Cost Comparison
Assumptions: $40,000 loan, 5-year repayment term, and a 7% average annual market return for the 401(k) opportunity cost.
| Feature | 401(k) Loan (8%) | HELOC (7.5%) |
| Monthly Payment | ~$811 | ~$801 |
| Total Interest Paid | $8,660 (Paid to Yourself) | $8,088 (Paid to Bank) |
| Out-of-Pocket Cost | $48,660 | $48,088 |
| Lost Market Gains | $7,600+ | $0 |
| Risk Factor | Job loss triggers immediate repayment | Home is collateral |
The Hidden “Triple Whammy” of the 401(k) Loan
While the table shows the 401(k) interest going “back to you,” it hides three significant financial traps:
- The Opportunity Cost: While you’re paying yourself 8%, you might be missing out on a bull market. Over 5 years, $40,000 invested in a balanced portfolio could easily earn $7,000 to $10,000 in growth. That is growth you can never get back.
- The Tax Trap: You pay back a 401(k) loan with after-tax dollars. However, when you withdraw that money in retirement, you will be taxed on it again. You are essentially paying the government twice on the interest portion of your loan.
The “Unemployed” Clause: If you lose your job or switch companies, most 401(k) plans require the loan to be paid back in full very quickly (often by the next tax filing deadline). If you can’t, the IRS treats it as a withdrawal, hitting you with income tax and a 10% early withdrawal penalty.
The Break-Even Math
If we assume you are paying back the $40,000 over 5 years, here is how the market return affects your final 401(k) balance compared to taking a HELOC:
| Annual Market Return | Result of Choosing the 401(k) Loan |
| 5% Return | Win: You “beat” the market by paying yourself 8%. Your account is $2,200 higher than if you’d kept it invested. |
| 8% Return | Break-Even: The interest you pay yourself exactly matches what the market would have done. |
| 10% Return | Loss: You are $3,100 behind because the market grew faster than your 8% loan interest. |
| 12% Return | Significant Loss: You are $6,400 behind in retirement savings. |
Why the “Break-Even” is actually higher
In a vacuum, 8% is your break-even. But in the real world, the break-even is usually higher (around 9% or 10%) because of the Tax Trap mentioned earlier.
When you use a HELOC, your $40,000 stays in the 401(k) and grows tax deferred. When you use a 401(k) loan, you are replacing “pre-tax” growth with “after-tax” interest payments. To truly break even, the market usually needs to perform significantly better than your loan rate to justify the tax disadvantage of the loan.
The Verdict
- If you are a conservative investor: (mostly bonds/stable value), the 8% 401(k) loan is likely a win because you are paying yourself a higher rate than your investments would likely earn.
If you are an aggressive investor: (S&P 500/Growth stocks), the HELOC is statistically the better play. History shows the market often returns more than 8-10% over 5-year stretches, meaning the 401(k) loan would cost you thousands in lost compounding
Which Should You Choose?
Choose the HELOC if: You have a stable home value and want to keep your retirement nest egg intact. Even though you’re paying a bank, the cost is often lower than the wealth you would lose by pulling money out of the market. Plus, if you use the HELOC for home improvements, the interest may even be tax deductible.
Choose the 401(k) Loan if: You have poor credit (making a HELOC impossible), you have absolute job security, and you are comfortable with the “double taxation” on the interest in exchange for not having a bank involved.
