Loan amortization is the process of paying interest and principal on a loan over a fixed time period.

Your interest is calculated as a fixed percentage of your remaining balance, so to keep payments even, your initial payments are directed more toward interest than paying down the principal. As time passes, more of your payment goes toward paying the principal until the loan is paid off.

Seems like pretty simple math — and it was until the decade after the Great Recession saw an explosion of student loan borrowing and the growth of negative amortization of student loans.

Before we get to the latest developments in student loan repayment policy, it’s important to understand how we got here.

What is student loan amortization?

Amortization refers to the process of paying back an installment loan, such as student debt, with fixed payments over a set period. Many student loans are amortized over 10 years and require fixed monthly payments. 

Depending on your loan, though, you might have a longer or shorter repayment period. As you pay back your debt, a part of each payment goes toward paying down interest charges, and the rest goes toward reducing your principal balance. 

“In a typical amortization schedule, a borrower’s monthly payment covers all of the accruing interest each month along with some principal, so that the overall balance gradually goes down over time until the loan has been paid in full by the end of the repayment period,” according to Adam Minsky, a student loan lawyer.

An example of student loan amortization

When you’re shopping for a student loan, whether public or private, the lender will show you an amortization schedule to give you an idea of how much you’ll have to pay each month. Here is an example of a five-year amortization schedule for a $1,000 student loan at 6% interest. (You can check your own details with a student loan calculator.)

You can see in the table that payments on interest go down and payments on principal go up over the life of the loan. Over five years, you pay a total of $1,160, which is the original $1,000 loan plus $160 in interest.

Amortization reveals the month-by-month process of paying your student loans back. While your monthly payments may never change, amortization can affect your debt in some significant ways.

How a repayment plan can change your amortization schedule

If you adjust your repayment terms, your student loan’s amortization will change as well. Adding years to repayment via switching repayment plans or by refinancing, for instance, typically reduces your monthly payments and leads to increased interest costs.

Between 2010 and 2020, the number of borrowers who enrolled in income-driven repayment (IDR) plans more than doubled for undergraduate borrowers and for graduate borrowers, adoption increased over sixfold. Many of these borrowers switched from plans with ten-year repayment windows and higher monthly payments to plans that based monthly payments on annual income.

These IDR plans were designed to make payments manageable while borrowers were getting started in their careers, and if after 20 to 25 years, the borrower’s income hadn’t risen to the level where she was still paying the loan, it would be forgiven. Unfortunately, one side effect of these programs was to create negative amortization of students’ loans where your payments aren’t enough to cover both interest and principal payments. 

When you enter negative amortization, the unpaid interest is added to the principal. The result was some lower-income borrowers found that their loans were growing year-over-year even though they were making monthly payments.

Negative amortization and the policy changes in the One Big Beautiful Bill Act (OBBBA)

Lawmakers addressed the issue of negative amortization in the One Big Beautiful Bill Act (OBBBA) signed into law on July 4, 2025. The bill represented a massive shift in the federal government’s approach to financing higher education.

Lawmakers sought to simplify the income-driven repayment system that had grown more complex over the last three decades. They argued that federal aid had contributed to tuition inflation and didn’t incentivize colleges to provide an education that would pay off student loans.

To control costs and ensure borrowers contributed more to their debt, Congress implemented several strict parameters:

• Elimination of $0 Payments: Lawmakers removed the possibility of a $0 monthly payment, requiring everyone to pay a minimum of $10 per month.
• Tiered Income Structure: Payments were set between 1% and 10% of a borrower’s Adjusted Gross Income (AGI), based on a tiered income bracket system.
• No Payment Caps: In a major shift, RAP eliminates the payment cap. Under older plans, a borrower’s IDR payment would never exceed the standard 10-year amount. Under RAP, high earners can be required to pay significantly more as their careers grow, effectively subsidizing the program.
• Strict Deferments: The bill eliminated economic hardship and unemployment deferments for new loans, drawing sharp criticism from consumer advocates.

Negative amortization was central to the debate over the structuring of these reforms. Lawmakers of both parties agreed that borrowers shouldn’t see their balances increase while making on-time payments.

To solve this, the OBBBA eliminated unpaid interest capitalization under the new RAP plan with two provisions: If a borrower’s income-based repayment doesn’t cover their monthly interest, the Department of Education waives the remaining unpaid interest. And if an on-time payment reduces the principal by less than $50, the government provides the difference to ensure the principal drops by at least that amount (or up to the full payment amount if the payment itself is under $50).

Making loan amortization work for you

The OBBBA provision that removes the cap on payments borrowers who are in the RAP program can be a major headache for workers whose salaries increase into the top tiers.

Joe Messinger of Capstone Partners crunched the numbers, and for earners above $100,000, the RAP plan costs more than the Tiered Standard repayment plan. As your income grows, so does your payment. For example, if you make $250,000 per year, Messenger calculates your monthly payment will balloon to an eye-watering $2,083.33 per month.

That extra money means you will pay off your loan faster — perhaps faster than the 10-year timeline of the Tiered Standard Plan. But is it a good idea for high earners? 

Getting out of debt faster is never a bad thing, but enrolling in RAP while also expecting to be a high earner takes away your ability to manage your cash flow. If your income is periodic or fluctuating but you’re still a high earner, you may find yourself short of cash in the lean months.

Making extra payments on your own terms under the Tiered standard plan, on the other hand, will also accelerate loan repayment and save you money on interest, but without the possibility of missing a payment.

If you have several high-interest loans, consolidating them into one lower-interest loan can also save money in the long run. But keep in mind that fees and resetting the amortization clock can actually add to your total payment.

Ultimately, understanding the mechanics of your loan’s amortization is the key to maintaining control over your financial future. 

While the reforms in the One Big Beautiful Bill Act successfully tackled the trap of negative amortization, the RAP plan’s uncapped payments mean it is no longer a set-it-and-forget-it solution for upwardly mobile professionals. 

By mastering how your principal and interest interact and strategically choosing a repayment plan that aligns with your income trajectory, you can avoid unexpected cash flow crunches, minimize your total interest costs, and eliminate your student debt on your own terms.