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What Is Business Term Loan Amortization?
Business term loan amortization is the process of paying down a loan through fixed periodic payments, where each payment covers both interest owed and a portion of the original principal. The schedule is structured so that after the final payment, your balance reaches exactly zero.
What makes amortization distinct is how the interest-to-principal ratio shifts over the loan's life. Early payments are weighted heavily toward interest because your balance is large, and later payments are weighted toward principal as that balance shrinks.
The math behind every payment uses the standard amortization formula: PMT = P × r(1+r)n / ((1+r)n - 1). In this formula, P is the loan amount, r is the monthly interest rate (annual rate divided by 12), and n is the total number of monthly payments.
This formula produces a payment that stays constant every month while the internal split between interest and principal silently shifts. Knowing this structure lets you make smarter decisions about prepayment, refinancing, and tax planning.
How the Amortization Schedule Works Month by Month
Each payment in an amortized loan is the same total dollar amount, but the share going to interest shrinks as your balance decreases. The interest portion is calculated fresh each month as: remaining balance × (annual rate / 12).
Take a $100,000 loan at 9% over 5 years as an example. The monthly payment works out to $2,076, with month one splitting as $750 in interest and $1,326 toward principal, leaving a balance of $98,674.
By month 36, the split has nearly reversed: only $354 goes to interest and $1,722 goes to principal. By the final month, interest drops to just $15 while principal takes almost the entire payment.
| Month | Payment | Interest | Principal | Balance |
|---|---|---|---|---|
| 1 | $2,076 | $750 | $1,326 | $98,674 |
| 12 | $2,076 | $636 | $1,439 | $83,417 |
| 24 | $2,076 | $501 | $1,574 | $65,278 |
| 36 | $2,076 | $354 | $1,722 | $45,438 |
| 48 | $2,076 | $192 | $1,884 | $23,737 |
| 60 | $2,076 | $15 | $2,060 | $0 |
Calculate Your Own Amortization Schedule
Enter your loan amount, rate, and term below to see your monthly payment and total interest cost. Add an optional extra payment to see how much time and interest you'd save.
Amortization Calculator
Payment shown excludes any extra amount you enter above; the other three figures reflect it.
How Extra Principal Payments Change Your Amortization
Extra principal payments reduce your outstanding balance immediately, which lowers every future month's interest charge. Even a modest amount applied early in the term compounds into real savings.
On the $100,000 example above, adding $300 to every payment cuts the term from 60 months to 51 months. Total interest drops from $24,550 to $20,614, a savings of $3,936.
The earlier you start making extra payments, the bigger the effect, because more of the balance is still outstanding. Extra payments made in the last year of a loan barely move the needle.
Amortized vs. Interest-Only Business Loans
An amortized loan requires payments that cover both interest and principal every month, steadily reducing your balance. An interest-only loan charges just the interest during a set period, leaving the full principal due at maturity.
Interest-only structures lower your monthly payment short-term, which can help cash flow during a slow season. But they dramatically increase total interest paid and leave a large balloon payment waiting at the end.
Most SBA and bank term loans are fully amortized from day one. Interest-only periods show up more often in bridge loans, construction financing, and some commercial real estate products.
What to Check Before You Sign an Amortization Schedule
Any reputable lender will provide a full amortization schedule before closing, not just a payment estimate. If a lender won't produce one, treat that as a warning sign.
Check whether the schedule assumes exactly on-time payments with no fees added to the balance. Ask specifically whether the lender allows extra principal payments without a prepayment penalty.
Compare the lender's numbers against your own calculation using the tool above or a spreadsheet. Small discrepancies can reveal rounding practices or fees folded into the rate.