When interest accrues and is added to the principal balance of a student loan, your total balance grows and you start paying interest on that new, higher amount. This makes the loan more expensive over time because interest is now effectively charging interest on itself.

What actually happens

When accrued interest is added (this is called ā€œcapitalizationā€):

  • The unpaid interest is rolled into your principal balance.

  • Your ā€œnew principalā€ becomes:
    previous principal + unpaid interest.

  • Future interest is now calculated on this bigger number, so the daily or monthly interest charge goes up.

Simple example

  • You borrow 5,0005,0005,000 at a certain rate and donā€™t pay interest while in school.
  • Over time, say 750750750 in interest builds up.
  • When it capitalizes, your principal becomes 5,7505,7505,750, and interest now accrues on 5,7505,7505,750, not 5,0005,0005,000.

That is the key effect: capitalized interest itself begins to generate more interest , which accelerates how fast your balance grows.

When this usually happens on student loans

Common moments when interest is added to principal (capitalized):

  • After you finish school and your grace period ends (for many unsubsidized loans).
  • After deferment or forbearance periods where interest was allowed to build up.
  • When you leave, enter, or change certain incomeā€‘driven repayment plans.

In all these cases, any unpaid interest sitting on the account may be added to the principal, and then interest resumes on the higher balance.

Why it matters for you

Capitalization can:

  • Increase the total amount youā€™ll pay over the life of the loan.
  • Raise your monthly payment under standard or fixed plans, since payments are based on the new higher principal.
  • Make it feel like your loans ā€œarenā€™t going down,ā€ because more interest is piling on a bigger base.

If possible, paying at least the accruing interest before it capitalizes (for example while in school or during a grace/deferment period) can help keep your principal lower and reduce how fast your balance grows.

Forum-style quick takeaway

When interest on a student loan gets added to the principal, your balance doesnā€™t just grow onceā€”it sets you up to pay even more interest in the future, because the loan now charges interest on a larger amount that includes past interest.

TL;DR:
When interest accrues and is added to the principal balance of a student loan, that interest becomes part of what you owe, and future interest is calculated on this new higher balance, making your loan more expensive over time.

Meta description (SEO):
Find out what happens when interest accrues and is added to the principal balance of a student loan, how capitalization works, and why it can significantly increase your total repayment cost.

Information gathered from public forums or data available on the internet and portrayed here.