A monthly payment is a cash commitment. It is not a complete description of a loan's cost. To understand the balance, separate principal, accrued interest, fees, and the order in which payments reach them.
Watch one payment move through a simple loan
Suppose an illustrative loan has $5,000 of interest-bearing principal, a 12% annual simple rate, a 365-day denominator, and 30 days since the last posting. Assume no fees and that payments go first to accrued interest, then principal. These are stated arithmetic assumptions, not universal contract terms.
| Step | Calculation | Result |
|---|---|---|
| Accrue interest | $5,000 × 0.12 × 30 ÷ 365 | $49.32, rounded once |
| Apply payment to interest | $200 − $49.32 | $150.68 left |
| Reduce principal | $5,000 − $150.68 | $4,849.32 principal |
If a contract instead used 360 as the denominator, the same example would accrue $50.00. Neither calculation establishes which convention a lender may lawfully apply. Request the convention, posting dates, and transaction history before alleging an error.
Interest rate, APR, and total cost answer different questions
- Interest rate
- The rate applied to a specified balance under the contract's method. A variable rate can change with an index or another permitted trigger.
- APR
- A standardized annual percentage rate calculated under the applicable disclosure rules. Included finance charges and timing matter; dividing fees by principal is not a reliable legal APR calculation.
- Amount financed
- A disclosure amount that can differ from the face balance or cash you receive, for example when a charge qualifies as a prepaid finance charge.
- Total of payments
- The scheduled aggregate payments under the disclosure assumptions. It is not necessarily today's payoff amount.
For covered closed-end transactions, Regulation Z's disclosure framework separates these items. Compare offers with the same borrowing amount and repayment assumptions; also compare the payment you can sustain and any collateral exposure.
Find the reason a balance keeps growing
Capitalization adds unpaid interest to principal. That differs from simply listing unpaid interest separately. Negative amortization occurs when payments do not cover the relevant accrual and the debt grows. A minimum payment may satisfy that month's requirement while making slow progress against principal.
A deferred-interest promotion can add interest accrued from the purchase date if its payoff conditions are not met. A true temporary zero rate does not accrue interest attributable to that zero-rate period. Locate the promotional expiration, deferred amount, allocation rules, and payoff figure. For a penalty rate or late fee, locate the trigger and applicable legal restriction; a charge appearing on a statement is not its own legal justification.
Before sending extra money, confirm its destination
- Ask for a dated payoff or principal-payment instruction, not just the statement balance.
- Check whether an extra payment reduces principal immediately, advances a due date, pays fees, or follows another allocation.
- Read any prepayment charge and unearned-interest refund provisions.
- Verify the next statement and retain the payment confirmation.
Prepayment disclosures describe specified terms; they do not by themselves establish every charge is lawful. For precomputed interest, a rebate or refund calculation can be a separate part of the payoff. Do not count that refund twice when comparing the quoted payoff with remaining scheduled payments.
Sources and further reading
General educational information. The original evidence, dates and recorded qualifications are available in the optional archive below.