Unpaid accrued interest is interest your lender has already earned on your loan but that you haven’t paid yet. It builds up between payments based on your interest rate and your remaining principal, and if a payment doesn’t cover it, the leftover sits on the loan as a separate balance that keeps growing. Left alone, that balance often gets folded into your principal later, which makes the loan more expensive overall.
How Interest Builds Up Between Payments
On most loans, interest starts accruing the day the money is disbursed and keeps accruing daily after that. The exact rules come from your loan contract and, for some loans, federal regulation.1Consumer Financial Protection Bureau. Student loan debt tips – Section: Understand what makes student loans unique Certain federal student loans are an exception: on subsidized loans, the government may pay the interest for you during set periods, such as while you’re in school or during some grace periods.
Simple interest is calculated on the original amount you borrowed. Compound interest is calculated on the principal plus interest that has already built up, so the balance grows faster because the rate applies to a larger number. Credit cards and mortgages commonly use daily compounding.
The basic math: take the current principal, multiply by the daily interest rate, then multiply by the number of days since your last payment. When you pay, the money generally goes to interest first, and anything left reduces the principal.
Why You End Up With Unpaid Interest
Unpaid accrued interest shows up whenever your payment is smaller than the interest that has built up since the last one. A few common situations cause this.
The first is forbearance. Depending on the loan agreement and program rules, forbearance might let you:2Legal Information Institute. 34 C.F.R. § 685.205
- Stop making payments for a short time
- Take longer to pay back the loan
- Make smaller monthly payments than what was first required
The second is missed or late payments. When you skip a monthly payment, the interest portion of that payment immediately becomes unpaid accrued interest, and daily interest keeps piling on top while you’re behind.
The third is negative amortization. Some loans set the minimum payment lower than the monthly interest charge on purpose. The uncovered interest becomes unpaid accrued interest, so the debt grows even when you pay on time, every time.
What Capitalization Does to Your Balance
Capitalization is when unpaid interest gets added directly to your principal.3Legal Information Institute. 34 C.F.R. § 685.202 On federal student loans, the government does this under program rules. Once it happens, that interest isn’t a side balance anymore; it’s part of a new, larger principal.
The new principal then accrues interest at the same rate. That’s the interest-on-interest cycle, and it raises the total you’ll pay over the life of the loan. Your monthly payment may stay the same, but you’re likely paying for longer.
Timing depends on the loan program or contract. In many federal programs, capitalization happens at the end of a period when payments were paused, such as a deferment or forbearance.3Legal Information Institute. 34 C.F.R. § 685.202 Because capitalization makes the debt more expensive, a common recommendation is to pay off the interest as it accrues, even when the loan lets you skip principal payments.
How to Track It and What It Means at Tax Time
Your servicer’s statements and account documents show how much interest has built up since your last payment and how the balance is moving. Checking these regularly is the easiest way to see what capitalization would cost you if you did nothing.
If you pay $600 or more in student loan interest during the year, the entity that received the payments must send you IRS Form 1098-E.4Internal Revenue Service. About Form 1098-E, Student Loan Interest Statement Taxpayers can generally deduct up to $2,500 of interest paid on qualified education loans, subject to income limits and other eligibility rules.5Office of the Law Revision Counsel. 26 U.S.C. § 221
You can only deduct interest in the year you actually pay it. Interest that has been capitalized is still interest for tax purposes, but you generally can’t deduct it until your payments cover those amounts.6Legal Information Institute. 26 C.F.R. § 1.221-1