Payments and interest on federal student loans were suspended early in the COVID-19 pandemic, providing financial relief to millions of borrowers. That suspension was extended eight times, but the end is finally near. Starting in October, borrowers must resume making payments.

While it's impossible to predict the exact impact on the economy or on any individual company, the sudden loss of hundreds of dollars per month in discretionary cash for millions of borrowers is going to have implications. One company that could see an outsize impact is e-commerce leader Amazon (AMZN 0.81%).

Less money to spend

Amazon is the king of convincing consumers to make impulse purchases. Amazon Prime removes almost all the friction from making a purchase. Shipping is free and fast -- sometimes same-day or overnight, even for inexpensive items.

A study by market researchers OnePoll found that the average American spends $5,400 annually on impulse purchases. About 21% of respondents tended to make impulse purchases online, but costly shipping was a barrier that stopped many of them from following through. Amazon has completely removed that problem with Prime.

Another study, this one from Morgan Stanley, found that 34% of respondents would be unable to make student loan payments at all once they restart. Only 29% of respondents were confident that they wouldn't need to adjust spending on other areas, and 37% expect to slash their spending.

While surveys are not fact, and what people say can be very different from what people do, lifestyle creep is real. For many consumers, money that would have gone toward student loans over the past three years has been spent on other stuff. That other stuff is now going to be on the chopping block as household budgets adjust to the new student loan reality.

The return of student loan payments is likely to hit many retailers, not just Amazon. Target, for example, was recently downgraded by JPMorgan due to the expected impact of student loan payments restarting. The typical Target customer, according to analytics firm Numerator, is between 35 and 44 years old with at least some college. Target's dependence on shoppers who likely have student loans was one reason for the downgrade.

The typical Amazon shopper looks similar, according to the same analytics firm. Those who are college-educated and between 35 and 44 years old appear to be Amazon's bread and butter, although the company is also popular with older age groups. Just like Target, Amazon will face the headwind of having a significant chunk of its customer base suddenly have less money to spend.

Already under pressure

Amazon's e-commerce business is already struggling a bit as consumers react to elevated inflation, rising interest rates, and economic uncertainty. The situation started looking better in the first quarter, with sales in the North America segment rising 11% year over year. Cost cutting has helped the bottom line, although Amazon's retail business barely produces any profit.

The return of student loan payments could throw a wrench into these recovery efforts. Amazon's typical customer may become slightly more cautious about buying items on a whim. Amazon-owned Whole Foods could lose some customers looking for lower prices on groceries. The advertising business, which depends on third-party sellers buying advertising space, could slow if overall demand weakens.

Amazon is already facing multiple challenges, including a slowdown in its cloud computing unit. Add the student loan payment restart to the list.