When you take out a student loan, the amount you owe grows because of interest. Interest is the cost of borrowing money, and it accrues—or adds up—over time. For federal and private student loans, interest typically accrues daily based on your loan’s interest rate and your current principal balance.
Understanding how interest accrues helps you plan payments and avoid surprises. This guide explains the basics, including how daily interest is calculated, when it starts, and what happens during grace periods or deferment.
How Is Student Loan Interest Calculated?
Most student loans use a formula that calculates interest daily. The formula is: (Interest Rate ÷ Number of Days in the Year) × Current Principal Balance = Daily Interest Amount.
For example, if you have a $10,000 loan with a 5% annual interest rate, your daily interest would be about $1.37. That amount is added to your loan each day, and then the next day’s interest is calculated on the new balance—this is called compounding.
However, not all loans compound the same way. Federal student loans use simple interest, which means interest is based only on the original principal, not on previously accrued interest. But if you don’t pay the accrued interest, it can capitalize—meaning it gets added to your principal—which causes future interest to be charged on a higher amount.
| Loan Type | Interest Accrual Method | When Interest Starts |
|---|---|---|
| Direct Subsidized Loan | Simple interest, no accrual during in-school or grace | After grace period ends |
| Direct Unsubsidized Loan | Simple interest, accrues from disbursement | Immediately |
| Private Student Loan | Varies—often simple or daily compounding | Usually immediately |
When Does Interest Start Accruing?
For most federal student loans, interest starts accruing as soon as the loan is disbursed—that is, when the money is sent to your school. The only exception is a Direct Subsidized Loan, where the government pays the interest while you are in school at least half-time, during the grace period, and during deferment.
For unsubsidized loans, interest accrues from day one, even while you’re still in school. If you don’t pay that interest during school, it will be added to your principal when you enter repayment—this is called capitalization.
Private student loans vary, but most start accruing interest immediately, regardless of your enrollment status. Always check your loan agreement for specifics.
What Is a Grace Period and How Does It Affect Interest?
A grace period is a set time after you graduate, leave school, or drop below half-time enrollment before you must start making payments. For most federal loans, the grace period is six months.
During the grace period on an unsubsidized loan, interest continues to accrue. That means your balance will be higher when you start repaying. For subsidized loans, interest does not accrue during the grace period.
If you can, consider paying the interest that accrues during your grace period. This prevents capitalization and keeps your principal lower, which reduces the total interest you’ll pay over the life of the loan.
What Is Capitalization and Why Does It Matter?
Capitalization is when unpaid interest is added to your principal balance. This increases the amount on which future interest is calculated, so your debt grows faster.
Capitalization can happen when you enter repayment after a grace period, after a deferment or forbearance, or if you leave the Income-Based Repayment plan. For example, if you have $5,000 in unpaid interest and a $20,000 principal, after capitalization your principal becomes $25,000, and interest is calculated on that higher amount.
To avoid capitalization, try to pay at least the interest that accrues each month. Even small payments can make a big difference over time.
How Does Interest Accrue During Deferment or Forbearance?
Deferment and forbearance allow you to temporarily pause payments, but interest still accrues in most cases. For unsubsidized loans and private loans, interest accrues during both deferment and forbearance.
For subsidized loans, interest does not accrue during an in-school deferment or the post-enrollment deferment, but it does accrue during forbearance. If you don’t pay the interest during these periods, it will be capitalized at the end.
Before you request a deferment or forbearance, ask your loan servicer if interest will accrue. If it will, calculate the potential cost and consider making voluntary interest payments to keep your balance from growing.
How Can You Reduce the Total Interest You Pay?
- Make payments while you’re in school—even small ones can reduce the principal and future interest.
- Pay more than the minimum monthly payment once you’re in repayment.
- Set up automatic payments; many servicers offer a 0.25% interest rate reduction.
- Consider making biweekly payments instead of monthly to reduce the principal faster.
- Refinance only if you can secure a lower interest rate and understand the trade-offs.
What Is the Difference Between Simple and Compound Interest?
Simple interest is calculated only on the original principal. Compound interest is calculated on the principal plus any accrued interest. Federal student loans use simple interest, but capitalization can make them behave like compound interest.
Private loans may use simple or compound interest, depending on the lender. Always read the loan terms to know which method applies.
In general, simple interest is better for you as a borrower because it grows more slowly. But even with simple interest, unpaid interest can capitalize and increase your balance.
How Does Daily Interest Affect Your Monthly Payment?
Your monthly payment is set based on your loan term and interest rate. However, the interest that accrues each day is added to your balance until you make a payment. When you pay, the payment first covers any accrued interest, and the remainder goes toward the principal.
If your monthly payment is less than the interest that accrues—such as in an income-driven repayment plan—your balance may grow even as you make payments. This is called negative amortization.
To avoid this, try to pay at least the monthly interest amount. You can find this by multiplying your daily interest by 30.
Practical Summary
Interest on student loans accrues daily based on your principal and interest rate. Federal subsidized loans don’t accrue interest during certain periods, but unsubsidized and private loans generally accrue from the start. To minimize total interest, pay at least the accruing interest whenever possible, avoid unnecessary deferments, and make extra payments when you can. Always check your loan agreement and talk to your servicer about how interest works for your specific loans.
Frequently Asked Questions
When does interest start accruing on student loans?
Interest starts accruing as soon as the loan is disbursed for most loans, except for subsidized federal loans where the government pays interest while you’re in school and during the grace period.
Does student loan interest accrue monthly or daily?
Most student loans accrue interest daily, which means the interest is calculated each day based on your current principal balance and annual interest rate.
What happens to unpaid interest on student loans?
Unpaid interest can be capitalized, meaning it is added to your principal balance, which increases the amount on which future interest is calculated.
How can I avoid paying too much interest on my student loans?
You can reduce interest by making payments while in school, paying more than the minimum each month, and avoiding deferment or forbearance unless absolutely necessary.
Is student loan interest tax deductible?
Yes, you may be able to deduct up to $2,500 of student loan interest paid during the year, but the deduction is subject to income limits and other requirements.
