I’m thinking of borrowing from my 401(k).
You’ve built a balance, and the plan will let you borrow against it: a low rate, no credit check, and the interest goes back into your own account. It feels like the smartest loan in the world. It’s also the one loan that quietly raids the one account you can never buy back time on.
It’s your future, on loan.
The day you borrow, that money leaves the market — and the market doesn’t wait for you to pay it back. Even if you repay every dollar on schedule, the cash you pulled out missed the years of growth it would have earned sitting still.
A $50,000 loan you pay back by 40 still costs your 65-year-old self about $0
You repay every dollar within five years — and at that point you're only about $11,000 behind. But the gap doesn't close. Left to compound the decades until you retire, it grows into the $64,000 hole you see here, on a single loan you paid back in full.
And that hole is the best case — it assumes you repay every payment on time, never lose the job that would make the balance come due, and never reach for the account again.
That gap is the quiet part of the deal. A dollar you pull out at 35 isn’t worth a dollar — it’s worth the ten or fifteen it would have become by 65, so breaking a $50,000 position’s growth costs your retired self tens of thousands, not the $11,000 you’re behind the day you finish repaying. And “I pay the interest to myself” doesn’t rescue it: that rate is almost always below what the market would have earned, paid with money out of your own pocket.
It rarely stays one loan.
The deepest cost isn’t on any chart: reaching into your retirement once makes the next time easier. A loan you couldn’t quite repay quietly becomes a cash-out. Years later the same habit returns — a chunk pulled at retirement to clear a debt that never really went away, and then too much too soon, because the balance has finally grown big enough to feel like it can spare it. Each reach costs another stretch of growth, and the debt underneath is still there. The first 401(k) loan is rarely the last withdrawal; it’s the one that teaches you the account is fair game.
The part that turns a loan into a disaster.
Here is the cost that should give you the most pause, and it has nothing to do with the rate. A 401(k) loan is tied to your job.
If you leave or lose your job, the whole balance usually comes due fast. If you can’t repay it (or put an equal amount of cash into an IRA or a new employer’s plan) by your tax-filing deadline, including any extension, it stops being a loan and becomes a withdrawal: you owe income tax on the entire amount, plus a 10% penalty on top if you’re under 59½. And the moment a layoff hits is exactly when you’re least able to write that check. A loan you took in a good year can detonate in a bad one.
The interest gets taxed twice.
A smaller leak, but a true one — and the one most people miss. The dollars you pay in interest take a tax hit going in and another coming out.
Normal 401(k) money is taxed once. The interest on a loan is taxed twice.
Your regular contributions go in before tax and are taxed only when you take them out. A loan's interest is different: you pay it with money that's already been taxed, and then it's taxed again on the way out.
It won’t make or break the decision (the principal you borrow isn’t double-taxed, only the interest), but it’s one more way the “almost free” loan quietly isn’t.
The cost that hides in plain sight.
The most expensive part is often the one nobody mentions: the employer match. If money is tight enough that you’re borrowing, it’s tight enough that you may trim your contributions to afford the loan payment — and the day you drop below the match, you start leaving free money on the table. No loan rate is good enough to make up for handing back a dollar-for-dollar match.
The one time it earns a look.
There is a single case where a 401(k) loan is the lesser evil, and it’s worth being honest about it:
The case for a 401(k) loan is a genuine emergency, not a convenience — the kind where it’s the last thing standing between you and losing the roof over your head: a foreclosure or eviction you can’t stop any other way, the rent that keeps you off the street. Against that, or against high-interest debt you truly can’t escape (a 25% credit card, a payday loan), the loan’s lower rate can be the better of two bad options. But even then the exception holds only if you keep contributing enough to capture your full match and you’re not about to change jobs. Miss either and the four costs above swallow whatever it saved you.
One move this week.
The loan button will still be there next week. Before you press it, give the alternatives a real look — they’re almost always cheaper than they feel.
Before you borrow a dollar from your 401(k), price out every other option first (your emergency fund, a lower-cost loan, trimming the expense itself), and if you still borrow, keep contributing enough to get the full match and don’t do it with a job change anywhere on the horizon. The balance you’ve built is the one pile of money that’s busy buying back your future. Borrow from almost anything else first.
The cheapest-looking loan is rarely the cheapest.
A 401(k) loan wins on the one number that’s easy to see, the rate, and loses on the four that aren’t: the growth that never happens, the tax bomb if your job ends, the twice-taxed interest, and the match you may give up. Add them together and “borrowing from yourself” usually costs more than the loan you were trying to avoid. Treat your retirement balance as the last place you reach, not the first.
- Even fully repaid, a $50K loan borrowed at 35 can leave you about $64,000 short at 65 — the gap doesn’t close, it compounds.
- Worse, it rarely stays one loan — reaching for the account once makes the next withdrawal easier, and each one costs more growth.
- “Paying interest to yourself” still loses: that rate is almost always below what the market would have earned.
- Lose your job and the balance comes due — unpaid, it becomes a withdrawal taxed as income, plus a 10% penalty under 59½.
- The interest is taxed twice, and trimming contributions to afford the payment can cost you the employer match.
- It earns a look only as a true last resort (keeping your home, escaping inescapable high-interest debt), and only if you keep the match and won’t change jobs.