Interest on most consumer debts and deposit accounts accrues daily, meaning the lender or bank runs a small interest calculation every calendar day you carry a balance. The main exception is a traditional fixed-rate mortgage, which accrues interest once a month. How often interest accrues matters because it decides whether paying early, paying extra, or paying more frequently actually lowers what you owe.
Daily Accrual vs. Monthly Accrual
With daily accrual, the lender divides your annual percentage rate by the number of days in the year to get a daily periodic rate, then multiplies that rate by your outstanding balance. On a $10,000 balance at 8.5% APR, roughly $2.33 in interest builds up every single day.
With monthly accrual, the lender runs the calculation once for the whole month, based on your balance at a set point in the cycle. Your balance sits still between those calculations, no matter what happens in between.
The practical difference shows up when you try to pay ahead. On a daily-accrual loan, sending money a week before the due date drops your principal that day and cuts the next day’s interest charge. On a monthly-accrual loan, the timing within the month has no effect on the interest you owe for that period. This is why “pay early” advice works for some loans and does nothing on others.
How Each Type of Account Accrues Interest
Credit Cards
Credit card issuers calculate interest daily using a daily periodic rate — your APR divided by 365 — applied to your average daily balance for the billing cycle.1Consumer Financial Protection Bureau. How Does My Credit Card Company Calculate the Amount of Interest I Owe? Every day, the issuer takes your current balance, multiplies it by the daily rate, and records that charge. At the end of the cycle, the daily charges are totaled and added to your statement.
On a $5,000 balance at 22% APR, the daily periodic rate is about 0.0603%. Roughly $3.01 accrues each day, or about $90 over a 30-day cycle. Next cycle’s interest is calculated on the new, larger balance.
Most cards offer a grace period, a window during which new purchases do not accrue interest at all. If you pay your full statement balance by the due date, the issuer cannot charge interest on those purchases, and federal law requires issuers to send your statement at least 21 days before the grace period expires.2eCFR. 12 CFR 1026.5 – General Disclosure Requirements The grace period only works if you started the cycle with a zero balance. Once you carry a balance from one cycle to the next, interest usually begins accruing on new purchases from the day they post, though issuers cannot charge retroactive interest on amounts you already repaid within a grace period.3Consumer Financial Protection Bureau. 12 CFR 1026.54 – Limitations on the Imposition of Finance Charges
Traditional Mortgages
Fixed-rate mortgages calculate interest monthly. The lender takes your annual rate, divides by 12, and applies that monthly rate to your outstanding principal at the start of the month. Paying a few days early inside the same month does not change the interest charge for that period.
Mortgage interest is also paid in arrears: each monthly payment covers the interest that built up during the previous month. That is why closing on a home purchase includes a prepaid interest charge covering the days between closing and the end of that month, before your first regular payment comes due.
Some newer mortgage products marketed as “simple interest” mortgages do accrue daily. On those loans, paying a few days early each month can add up over a 30-year term because your principal drops sooner and the next day’s interest is lower. Check your promissory note before assuming which type you have.
Federal Student Loans
Federal student loans use daily simple interest. The formula multiplies your outstanding principal by an interest rate factor (your rate divided by the number of days in the year), then by the number of days since your last payment.4Federal Student Aid. Federal Interest Rates and Fees Because interest builds every day, paying more often or paying extra reduces your principal faster and lowers your total interest over the life of the loan. Even an extra $25 or $50 a month compounds in your favor over a 10- or 20-year repayment term.
Federal student loan interest does not automatically fold into your balance the way credit card interest does. Accrued but unpaid interest sits separately from your principal until a triggering event causes it to capitalize — for example, after a deferment period on an unsubsidized loan, or when you leave or no longer qualify for income-based repayment.4Federal Student Aid. Federal Interest Rates and Fees Once it capitalizes, your new higher principal generates more daily interest going forward.
Auto Loans
Auto loans come in two flavors, and the accrual method decides whether early payoff saves you anything:
- Simple interest auto loans calculate interest on your actual outstanding balance, either daily or monthly. Extra payments shrink your principal and reduce future interest.
- Precomputed interest auto loans calculate all the interest you will owe over the full term upfront and bake it into the payment schedule. Extra payments do not reduce the principal or the total interest owed.5Consumer Financial Protection Bureau. What’s the Difference Between a Simple Interest Rate and Precomputed Interest on an Auto Loan
Check your retail installment contract before committing to an early payoff strategy. On a precomputed loan, sending an extra $100 a month has no effect on the interest already locked in.
HELOCs
Home equity lines of credit accrue interest daily, similar to credit cards. The lender takes your average daily balance, multiplies by your interest rate, divides by 365, and multiplies by the number of days in the billing cycle. HELOCs also carry variable rates tied to the prime rate plus a margin, so the daily interest charge can change from month to month even if you do not draw additional funds.
Savings Accounts and CDs
Savings accounts and certificates of deposit typically accrue interest daily but credit it to your account monthly. A CD with a $10,000 principal earns a small amount each day, but the balance only ticks up on your statement date. Regulation DD requires banks to disclose both the compounding frequency and the crediting frequency, so you know when earned interest actually becomes available.6eCFR. 12 CFR Part 1030 – Truth in Savings (Regulation DD)
The gap between daily accrual and monthly crediting matters if you withdraw early. Interest that has accrued but not yet been credited may be forfeited, and CDs typically carry an early withdrawal penalty on top of that.
Accrual Is Not the Same as Compounding
Accrual and compounding are two separate steps. Accrual is the calculation that tells you how much interest has built up. Compounding is the moment that calculated interest gets added to your principal, so future interest is charged on the larger amount. A loan can accrue daily but only compound monthly, which means the interest-on-interest effect kicks in once a month rather than every day.
Compounding frequency changes what you actually pay or earn. A 5% rate compounded daily produces a higher effective annual cost than a 5% rate compounded annually, because each day’s small interest charge starts generating its own interest the next day. For deposit accounts, Regulation DD requires banks to express this combined effect as the annual percentage yield so you can compare accounts on equal terms.6eCFR. 12 CFR Part 1030 – Truth in Savings (Regulation DD) The APY formula accounts for both the interest rate and the compounding frequency over a 365-day period.7Legal Information Institute. Appendix A to Part 1030 – Annual Percentage Yield Calculation For borrowers, the equivalent figure is the APR. Comparing APY across deposit offers, or APR across loan offers, is more reliable than comparing stated rates.
The 360-Day vs. 365-Day Year
Not every lender divides your APR by the same number of days. Two conventions exist. The 365-day method (sometimes called actual/365) divides the APR by real calendar days and produces a slightly lower daily rate. The 360-day method, sometimes called the “banker’s year,” assumes twelve 30-day months and produces a slightly higher daily rate because the same annual interest is spread over fewer days.
The difference looks small day to day but compounds over long-term loans. On a $300,000 mortgage at 7%, a 360-day year adds roughly $1.15 more in daily interest than a 365-day year. Over 30 years, that is a meaningful sum. Your loan documents specify which method applies.
In a leap year, lenders using the 365-day method generally switch to 366 days for that calendar year, slightly reducing the daily rate. Lenders using the 360-day method ignore leap years, since the calculation is not tied to real calendar days.
Where to Find Your Own Accrual Terms
Every financial product comes with disclosure documents that spell out how often interest accrues, how often it compounds, and whether a grace period applies.
- Credit cards: the disclosure table (commonly called the Schumer Box) in your card agreement or application shows your APR, balance calculation method, and grace period length in a standardized format required by federal law.8Office of the Law Revision Counsel. 15 USC 1637 – Open End Consumer Credit Plans
- Mortgages: the Loan Estimate you received before closing discloses the product type, rate, and projected payments in a standardized format. Your promissory note specifies whether the lender uses a 360-day or 365-day year.9eCFR. 12 CFR 1026.37 – Content of Disclosures for Certain Mortgage Transactions (Loan Estimate)
- Savings accounts and CDs: the account disclosure you received at opening must state the compounding frequency, crediting frequency, and APY.6eCFR. 12 CFR Part 1030 – Truth in Savings (Regulation DD)
- Student loans: your servicer’s website and your original Master Promissory Note detail the interest rate, accrual method, and capitalization triggers.
- Auto loans: your retail installment contract states whether the loan uses simple or precomputed interest, along with the APR and payment schedule.
If you cannot find these documents, contact your lender or servicer directly. Federal law requires them to provide this information, and having it in front of you is the only reliable way to know exactly how your balance is growing each day.