In 2019, author and professor Lacy M. Johnson shared some statistics about her student loan debt on Twitter. After graduating with an initial balance of $70,000 and faithfully making about $60,000 in payments over the last 11 years, her new balance has fallen all the way down to…$70,000.

In the responses to her tweet, dozens of users shared similar stories. A woman who began with $120,000 in debt, and in seven years, never missed a payment, saw her balance balloon to $137,000. Another who’s paid more than $20,000 on an $80,000 debt still carries a $78,000 balance.

The thread reminded me of a former professor, who I’m friends with on social media and who once posted about his wife’s student loan dilemma: when she started paying them back, the monthly interest was greater than her monthly payment. Despite all the money they were putting into their loans, the balance just kept rising.

Despite all the money they were putting into their loans, the balance just kept rising.

As a senior in college, his post terrified me. I didn’t understand how it was possible. How could the interest be that high? Where was their money going? Why wasn’t the balance shrinking even though they were making payments?

But after navigating my own student loan journey, which combines both federal and private loans, I’ve come to understand the source of the problem: these borrowers aren’t on a fixed repayment plan.

For every other type of loan, repayment plans depend on a fixed amount of time. A mortgage, for instance, usually takes 30 years. The average length of a car loan is almost 6 years. A

nd personal loans vary by lender, ranging anywhere from 1 to 5 years. Fixed repayment plans like these ensure that no matter the interest rate, the length of the loan, or the balance, at least some part of your monthly payment goes toward paying down the principal.

But with federal student loans, the government offers many other types of repayment plans that don’t depend on a fixed timeline.

Rather, options like the Pay-As-You-Earn and Income-Based Repayment plans allow borrowers to make monthly payments calculated according to their income and not according to whether that payment will actually reduce the balance of the loan over time.

This is why your balance never goes down.

Consider my wife’s $28,000 federal student loan debt, which has an average interest rate of 4.27%. With the Pay-As-You-Earn plan, borrowers pay 10% of their discretionary income (defined as your total income minus 150% of the poverty guideline for your household size).

In our case, had we chosen that option, our monthly payment would have been $139. But the initial monthly interest was $100, which means only $39 would have gone toward reducing the balance. And at that rate, it would have taken 30 YEARS to pay off.

If the interest rate was 2% higher (as is typically the case with graduate loans), the interest would have been greater than our monthly payment, locking us into a loan that never shrinks — but eats our money anyway.

Instead, we treated our public debt the way we were forced to treat our private debt: with a fixed repayment term (usually 10 years) regardless of income. Now, we pay $325/month on those loans, $225 of which goes toward reducing the balance.

As you consider your repayment options, I completely understand the temptation (perhaps even the necessity) to take the lower monthly payment offered by the Pay-As-You-Earn and Income-Driven Repayment plans.

To be clear, I support total student loan forgiveness and sympathize with the heavy burden of these kinds of unmanageable loans, but since we’re not there yet, I highly encourage taking either the Standard, Graduated, or Extended Repayment plans (all of which operate on a 10–25-year term).

And if you must use an income-based plan, use the amortization schedule generated by this loan repayment calculator to determine your monthly interest and ensure your payment is at least that high — and, if possible, try to put in a little extra so you’re paying down the principal, too (which will, in turn, lower the interest each month).

It’ll be hard, but if you find yourself in a situation like Lacy Johnson’s, check your account statements and use these resources to calculate your monthly interest and get ahead of it. Otherwise, you may be forever throwing your money away on a seemingly endless loan.