Why this matters
Accrued interest between payments determines the extra dollars that get added to your next statement or payoff figure. For borrowers, it explains why missing, delaying, or making a payment early changes how much you ultimately owe. For servicers and investors, accurate accruals ensure correct cash flows and legal compliance.
Basic calculation (step‑by‑step)
- Find the outstanding principal on the date interest starts accruing (P).
- Determine the contract annual interest rate (r), expressed as a decimal (for 5%, r = 0.05).
- Identify the day‑count convention your lender uses (common options: actual/365, actual/360, or 30/360).
- Count the number of days between the last payment date and the date you’re calculating (d).
- Compute: Accrued interest = P × r × (d ÷ D), where D is the day‑count base (365, 360, or 360 with 30‑day months).
Examples that show the difference
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Monthly method (typical consumer mortgage statement): many servicers use a simple monthly rate: Monthly interest = P × (r ÷ 12). For a $150,000 loan at 5% annual interest, one month’s interest ≈ $150,000 × (0.05 ÷ 12) = $625.00.
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Actual‑days method: Using actual/365, the same loan for a 30‑day gap gives: $150,000 × 0.05 × (30 ÷ 365) ≈ $616.44. Lenders may choose one method in the note—check your loan contract.
Key variations and what to watch for
- Day‑count rules matter: Commercial loans and some bonds often use actual/360, which slightly increases daily interest compared with actual/365. Student loans and mortgages typically use monthly or actual/365 but read your promissory note.
- Capitalization: Unpaid accrued interest can be added (capitalized) to principal at specified times (e.g., at the end of forbearance or deferment). Capitalization increases future interest because interest is then charged on the larger principal. See how capitalization affects balances in our article on why interest capitalization increases your student loan balance (https://finhelp.io/glossary/why-interest-capitalization-increases-your-student-loan-balance/).
- Forbearance and deferment: Interest often continues to accrue during these periods unless a loan specifically suspends accrual. For details on accrual during forbearance, see How Accrued Interest Is Calculated During Loan Forbearance (https://finhelp.io/glossary/how-accrued-interest-is-calculated-during-loan-forbearance/).
- Interest method: Understand whether your loan uses simple (non‑compounding) or accrual methods—compare basics in our Accrual vs Simple Interest overview (https://finhelp.io/glossary/accrual-vs-simple-interest-how-interest-is-calculated-on-loans/).
Common real‑world situations
- Missed payment: Missing a due date doesn’t erase interest; it simply means interest continues to accrue on the outstanding principal until paid.
- Early payoff: Lenders will supply a payoff statement that includes accrued interest to the payoff date—always request a payoff figure dated the day you plan to pay.
- Refinancing mid‑cycle: If you refinance between scheduled payments you will usually owe accrued interest to the payoff date; the new lender’s first payment may include previously accrued interest.
Practical tips to reduce accrued interest costs
- Pay on or before the due date, or make extra principal payments to shorten the accrual base.
- If you plan to pause payments (deferment/forbearance), ask whether interest will continue to accrue and whether it will be capitalized. (See the article about accrual during forbearance linked above.)
- When paying off a loan, request a same‑day payoff statement to avoid unexpected accrued interest being added after you initiate payment.
- Consider timing: making payments early in the billing cycle reduces the number of accrual days before the lender posts the payment.
A practitioner’s note
In my work advising borrowers and small businesses, I’ve seen two frequent client errors: relying on a simple monthly estimate when the contract uses actual‑day accruals, and not accounting for capitalization after forbearance. Both can add hundreds to thousands of dollars over a loan’s life—so verify the note’s calculation method and request payoff amounts in writing.
Authoritative sources and where to read more
- Consumer Financial Protection Bureau — general borrower resources: https://www.consumerfinance.gov/
- IRS Publication 550 (investments and accrued interest discussion for tax reporting): https://www.irs.gov/pub/irs-pdf/p550.pdf
- Bankrate explainer on accrued interest: https://www.bankrate.com/loans/what-is-accrued-interest/
Disclaimer
This page is educational and does not constitute personalized financial or legal advice. Loan contracts vary; for specific balances, ask your servicer for a written payoff statement or consult a certified financial planner, attorney, or tax professional.
