Direct answer
Extra amounts intended as principal paydown should reduce balance and future interest. Servicers differ—confirm posting rules.
Ask your servicer
- Does it advance the due date only?
- Does it sit in suspense?
- Does it reduce principal immediately?
Model it
Amortization — add prepayment scenarios where supported.
Core lesson
Go deeper: Loan payments explained.
Use the calculator
FAQ
- Is extra payment always principal?
Only if applied to principal per loan terms and servicer processing.