Written byA flat rate is an interest method that charges a fixed percentage of the original principal for every year of the term, ignoring the balance you have repaid.
Also known as: flat rate interest, flat-rate loan
Key points
- Interest is worked out on the original loan amount for the whole term, not on the balance that falls as you repay.
- That makes a quoted flat rate look lower than it is, because the reducing balance equivalent is usually higher.
- For regulated consumer credit a comparison rate helps, but for dealer and equipment finance compare the total cost over the term.
- Ask for the total interest, the total repayable and a full repayment schedule before comparing quotes.
- "Flat rate" also describes fixed-fee pricing: one charge for a service no matter how much you use it.
How flat rate interest works
With a flat rate, the lender multiplies the amount borrowed by the rate and by the number of years, adds that interest to the loan, then divides the total by the number of repayments. Every repayment is the same size, and the interest charge never falls, because it was set at the start against the full amount.
A reducing balance loan works the other way. Interest is charged on what you still owe, so the interest portion of each repayment shrinks as the balance comes down. Converting a flat rate to an effective annual rate is the only way to compare the two, and an exact conversion normally needs a spreadsheet or financial calculator.
Where you see flat rates
Flat rates turn up in dealer car finance, in hire purchase and dealer packages aimed at tradies and small businesses, in bundled equipment finance deals, and in short-term arrangements where simple interest is applied to the principal. The same phrase also covers fixed-fee pricing, such as a set project charge or a flat delivery fee, which is a different idea entirely.
Check the wording on any quote. A flat fee for a service is plain enough. Flat-rate interest on credit needs converting before you can hold it beside a car loan or any other offer quoted on a reducing balance.
What to check before you sign
Treat a very low flat rate headline with no total cost figures as a reason to ask more questions. Missing detail on fees, on a balloon payment or on early repayment penalties belongs in the same category, as does pressure to take add-on insurance you did not ask for.
Ask for a written quote showing the total interest, the total repayable, every fee and the full repayment schedule, and confirm how deposits, trade-ins and residuals are treated. For vehicle and equipment finance, check how the lender registers its security on the PPSR. For regulated consumer credit, lenders must set out fees and key terms in the credit contract. Business finance is not covered by those rules, so ask for the detail in writing.
Not to be confused with
- Comparison rate
- a comparison rate expresses cost on a reducing balance and includes most fees, so it cannot be read against a quoted flat rate
- Fixed rate
- a fixed rate is about the rate not moving, not about how the interest is calculated
Frequently asked questions
Is a flat rate cheaper than a reducing balance rate?
Not necessarily, and usually not. A low flat rate can still work out more expensive, because interest is charged on the full amount borrowed for the whole term. Convert it to a reducing balance equivalent before deciding which offer actually costs less.
How do I convert a flat rate to an effective rate?
Use the constant ratio approximation: multiply the total interest by two and by the number of payments a year, then divide by the principal multiplied by the total number of payments over the loan plus one. For a loan repaid in regular instalments that lands at roughly double the quoted flat rate. For an exact figure, solve the present value equation in a spreadsheet.
Where are flat rates commonly used?
Dealer car finance, hire purchase, tradie and equipment packages, and some short-term loans. The phrase also covers fixed-fee pricing outside lending, such as a flat accounting fee or flat-rate postage, where one charge applies no matter how much you use.
Are flat rate fees negotiable?
Often yes. Ask the lender to itemise every fee, then negotiate or take the quote to other lenders. Comparing a dealer's flat rate quote against a standalone car loan or an equipment finance offer can reveal a meaningful difference in what you repay.
What should I ask a lender before signing?
Ask for the total interest, the total repayable, the effective rate, a full repayment schedule, every fee, the early repayment terms, and whether any insurance or add-on is optional. Get the answers in writing rather than over the counter.
Related terms
Broader term: Rate
Comparison rate
A comparison rate is a single annual percentage that combines a loan's interest rate with most upfront and ongoing fees to show its ongoing cost more clearly.
Read definitionSimple interest
Simple interest is interest calculated only on the original principal, never on interest already added, which keeps the charge flat across the term.
Read definitionFixed rate
A fixed rate is an interest rate locked in for a set term, so the rate and usually the repayments do not change until that term ends.
Read definitionInterest
Interest is the price of using money: what a borrower pays on a loan, or a saver earns on a deposit, expressed as a percentage rate on the principal.
Read definitionHire purchase
Hire purchase is a finance agreement where a financier buys an asset and hires it to you for fixed instalments, with ownership passing to you at the final payment.
Read definitionEquipment finance
Equipment finance is business finance used to buy or lease machinery, vehicles and other equipment, where the equipment itself secures the loan or is owned by the financier.
Read definitionGo deeper
Sources
This article is general information only and is not financial advice.