Pay Off Debt or Invest? One Number Decides It (And We Ignored It Anyway)

“Should I pay off my debt or invest?” is the most common money question I get, and it has a genuinely clean answer that fits on one line.

Then there’s the answer we actually used when we paid off $62,000, which broke the clean rule on purpose. Both parts matter, so here’s both.

Not financial advice – our approach and the reasoning behind it. Do your own research.

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The Clean Answer: Compare Two Rates

Paying off debt gives you a guaranteed, risk-free, tax-free return equal to the interest rate. Investing gives you an expected return that is neither guaranteed nor risk-free.

So the comparison is just: is my debt’s interest rate higher than what I could reasonably expect to earn?

Concrete version. You have $10,000 sitting there and a $10,000 credit card balance at 22%:

• Pay off the card: you stop paying $2,200 a year in interest. Guaranteed. No market can take it away.
• Invest it at an assumed 8%: about $800 a year, on average, in a good decade, with a real chance of being down 30% next year.

That’s not close. It’s a guaranteed 22% versus a hopeful 8%. There is no investment I’d recommend to anyone that reliably beats “stop paying 22%,” and anybody selling you one should make you suspicious.

The Tiers I Actually Use

Above roughly 7-8%: pay it off first. Credit cards, personal loans, most car loans, payday anything. At these rates the debt is compounding against you faster than a portfolio compounds for you. You’re running the machine from the compound growth math in reverse, and the reverse gear is faster because it never has a down year in your favor.

Roughly 4-7%: it’s genuinely a judgment call. Some student loans, some car loans. The expected math slightly favors investing; the certainty favors paying off. Nobody should tell you this one is obvious. Pick based on how much the debt weighs on you, and don’t let anyone make you feel dumb either way.

Under about 4%: I’d generally invest. Low-rate mortgages, subsidized loans. Paying off a 3% loan to avoid 3% interest while giving up a reasonably expected 8% is a choice you’re allowed to make – it’s just an expensive kind of peace of mind, and you should know that’s what you’re buying.

Three Things That Come Before Either One

1. Take the full employer match, always. If your employer matches retirement contributions, that’s typically an instant 50-100% return on the matched portion. Nothing in this article beats that – not even a 22% credit card. Take the match, then attack the debt with everything else.

2. Build a small cash buffer first. This is the mistake I see constantly: someone throws every dollar at debt, keeps zero cash, and then the transmission goes and the whole balance lands right back on the card. You didn’t pay off debt, you took a lap. Even one month of expenses in cash breaks that cycle – ours sits in a Marcus savings account, kept separate from checking so it can’t get spent by accident – which is most of why my emergency fund sits in boring savings earning almost nothing.

3. Check whether you can lower the rate. A balance transfer, a refinance, or a negotiated rate can turn a 22% problem into a 6% problem, which changes which tier you’re even in. Do this before optimizing anything else – it’s the cheapest hour of work available.

Where We Broke the Rule

Now the honest part. The mathematically optimal way to pay off multiple debts is highest interest rate first – the avalanche. It minimizes total interest paid, and it isn’t debatable.

We used the snowball instead: smallest balance first, regardless of rate. That method is, strictly speaking, worse. It cost us money.

I’d do it again, and here’s why. When we started, the pile felt undefeatable. Killing the smallest balance in the first six weeks gave us an actual win – one fewer account, one fewer payment, visible progress on a laminated list in front of the computer. That win is what made month four survivable, and month four is where most people quit.

The full version of how that year went is in how we eliminated $62,000 of debt in twelve months. The lesson I took from it: the optimal plan you abandon in month four is worth far less than the slightly suboptimal plan you finish.

That’s the same trade I make everywhere in my money life now, and it’s the same reason I described dollar-cost averaging as a behavior tool rather than a math edge. Finishing beats optimizing.

One caveat so I’m not being sloppy: the gap between snowball and avalanche is small when your rates are similar. If you’ve got one card at 26% and everything else at 5%, kill the 26% first regardless of balance. Don’t let a nice story cost you thousands.

The Part Nobody Talks About: What Happens After

Here’s what actually surprised me about becoming debt free. The money wasn’t the main thing.

Our minimum payments had been eating a serious chunk of every month. The day they stopped, that entire amount became available – and that freed-up monthly number is what now goes into investments automatically. The debt payoff didn’t just end a cost; it created the contribution that’s been compounding ever since.

And it changed what we were willing to consider. Carrying debt makes you conservative in ways you don’t notice. Without it, taking a swing at a side business felt survivable instead of reckless, which is what eventually made the whole cash-flow business path possible for us.

The rate math tells you what to do. It doesn’t capture that being debt free changes the person making the next decision.

The Whole Thing, In Order

1. Take any employer match in full. Free money, first, always.
2. Get one month of expenses in cash so surprises don’t reload the debt.
3. Try to lower your rates – transfer, refinance, negotiate.
4. Attack everything above ~7-8%. Avalanche if you’re disciplined, snowball if you need the wins. Finishing is what counts.
5. Finish the emergency fund properly.
6. Then invest the freed-up payment automatically, forever – ours goes into a broad index fund at Schwab the day after payday.

Steps 4 through 6 are the whole engine: debt payments become investment contributions without your lifestyle ever seeing the money. That’s how the flat early years in the first $100,000 get shorter.

If you’re staring at a balance right now and it feels like too much – it isn’t. We looked at $62,000 and felt exactly that. Write the number down, pick the method you’ll actually stick with, and start this month rather than the perfect one.