Imagine you had to do your taxes every year by paper. Spare a thought for millions of borrowers who now have to do just that when it comes to their college loans.

Some of the nation’s most vulnerable student loan borrowers could have more trouble managing their debts thanks to the recent outage of a government tool that’s expected to last six months, the federal consumer watchdog and borrower advocates are warning. The warning comes as lawmakers are set to review the decision to take down the tool, known as the IRS data retrieval tool, as part of a hearing hosted Wednesday by the House of Representatives committee on oversight and government reform. Much of the attention and outrage surrounding the tool’s outage has focused on students applying for college, who use it streamline the process of applying for financial aid.

But without the tool, student loan borrowers will also likely find it more difficult to remain on manageable repayment programs. Borrowers using programs offered by the federal government that allow them to pay off their student debt according to their income, rely on the tool to seamlessly re-certify their income with student loan servicers, the companies that manage the student loan repayment process.

“ Without this online tool, student loan borrowers are forced to turn to a complicated paper process that’s particularly difficult for low-income and other vulnerable borrowers, such as senior citizens, to navigate. ”

Now, they’re forced to turn to a complicated paper process that’s particularly difficult for low-income and other vulnerable borrowers, such as senior citizens, to navigate, advocates say. If borrowers miss deadlines to re-certify their income under the plans, their payments could suddenly spike. They’re also at risk of having the interest capitalize on their debt. “I just foresee a lot of delays and a lot of errors, and these delays and errors are going to be costly for borrowers,” said Persis Yu, the director of the student loan borrower assistance project at the National Consumer Law Center.

Yu sent a letter to the Consumer Financial Protection Bureau and the Department of Education last month asking what steps the agencies are taking to ensure that borrowers have access to their rights as they contend with the tool’s outage. In the past, borrowers have struggled to work with servicers to re-certify their incomes using the paper application and alternative documentation of their income, according to CFPB reports. That challenge is one of many documented by the CFPB that suggest servicers often don’t provide borrowers with the right or enough information to successfully manage their student loans.

In her letter, Yu noted that servicers haven’t been communicating clearly with borrowers about the tool’s outage, which is particularly problematic, given that without the tool, a normally 15-minute process could take several days as borrowers work to track down the relevant documentation and mail in their forms. What’s more, the tool’s outage will likely result in a much higher volume of paper applications, Yu noted in her letter, which could lead to further hold-ups out of borrowers’ control. “When things are good there are problems, so this is ultimately really concerning given that we know that this vital tool is down,” Yu said.

Seth Frotman, the student loan ombudsman at the CFPB, echoed Yu’s concerns in a response he sent Tuesday to her letter. He reminded borrowers that they’re guaranteed certain rights, while navigating the income-driven repayment program, including the right to use documentation other than their tax returns to prove their income, protection from unexpected jumps in payment or periods of forbearance — a payment status that allows borrowers to pause their payments, but where interest capitalizes on the loan — as long as the borrower submits their paperwork on time and a grace period that allows borrowers 10 extra days to complete their recertification application.

The CFPB is “closely monitoring” student loan servicers “to ensure that student loan borrowers are treated fairly, including the anticipated millions of more student loan borrowers who will have to manually submit income documentation,” Frotman’s letter reads.