It's no secret that it can be difficult for student loan borrowers to manage both making their debt payments and saving for retirement.

Student loans come with a minimum monthly payment that borrowers have to meet to keep their loans — and as a result, their credit history — in good standing. While there's no requirement to contribute to a 401(k) or other retirement account, it's smart to get started on saving early.

Consequently, those with student loan payments contribute at a lower rate and have smaller overall balances in their 401(k) accounts, a study from the Employee Benefit Research Institute recently confirmed.

The study examined the retirement savings habits of more than 50,000 participants between 2017 and 2019 to see how student loan payments affected their contributions.

While a higher salary does correlate with higher 401(k) balances and contribution rates overall, it doesn't close the gap between those making student loan payments and those who aren't making such payments. The difference in 401(k) account balances was especially pronounced among those who earn $55,000 a year or more, compared with those earning less.

In fact, employees with student loan payments who earn $55,000 a year or more and have been at their company for five years or less have average 401(k) balances 36% lower than those without payments, the EBRI found.

How student loan payments affect 401(k) balances

Naturally, employees consistently had higher average 401(k) account balances the longer they'd been with a company and the higher their salary, regardless of student loan payment status, the EBRI found.

But the gap between balances for those making student loan payments and those who aren't is surprisingly smaller among lower-earning employees than higher earners. For employees earning less than $55,000 a year, those without student loan payments had balances about 4.5% higher on average than those with student loan payments, regardless of tenure. 

For higher earners, the difference in average balances between those who are paying off student loans and those who aren't was much larger — about 20% higher, on average.

Change in payment status slightly affects 401(k) contributions

When they were able to stop making student loan payments, 32% of employees increased their 401(k) contributions, the study found. It examined participants' behaviors from 2017 to 2019, so the stopping or resuming of student loan payments was due to individual circumstances, not the Covid-19 pandemic forbearance that paused all payments for federal borrowers.

Across income groups, employees changed their 401(k) contributions at similar rates when their student loan payments ended, though lower earners were slightly more likely to increase their withholding. Just 31% of employees earning $55,000 a year or more increased their 401(k) contributions when they stopped making student loan payments compared with 33% of those earning smaller salaries.

Lower earners were also less likely to reduce their contributions when they started making student loan payments. Just 21% of those earning less than $55,000 lowered their 401(k) contributions as they started making payments, compared with 29% of the higher earning group, the EBRI found. 

"[It's] less disposable income that [borrowers] have, so it's likely a fear reaction," Sam Silberstein, a certified financial planner and certified student loan professional with Student Loan Planner, tells CNBC Make It. "A lot of people [reduce retirement contributions] before they even feel the impact of the student loan payments."

However, the size of the initial contribution rate may play a factor, too. Those contributing at higher rates may have more wiggle room. 

Silberstein says it makes sense, especially for lower earners, to look to their payroll deductions when they need to make room in their budget for student loan payments.

"Your first reaction is going to be money that you don't necessarily see come into your bank account, such as automatic salary deferments to retirement," she says.

Where you should put your paycheck

Your individual situation may require you to prioritize your debt payments while hopefully still being able to save what you can for retirement. 

But if you're someone with the flexibility to play around with the ideas of paying off your debt faster or saving even more for retirement, there are a few things to consider.

You might be able to lower your student loan payment just by switching your payment plan if you're a federal borrower. Getting on an income-driven repayment plan such as the Saving on a Valuable Education plan can lower your monthly payment, depending on how much you're making. 

On the other hand, lowering your net income by increasing your pretax retirement deductions can actually be a beneficial move because doing so lowers your adjusted gross income, which is used to calculate your student loan payment on an IDR plan.

"It is a way to increase your net worth on two fronts," Silberstein says.

It may seem counterintuitive to lower your income to build wealth, but Silberstein says you're not actually losing money, you're just putting it somewhere else.

"Not only are you paying yourself, but you're decreasing the amount of cash outflow," she says, referring to your discretionary income, which is what your student loan servicer looks at to determine your payment on an IDR plan.

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