About the Seller Financing Calculator
In a seller-financed sale, also called owner financing or a seller carry-back, the seller acts as the bank. Instead of the buyer getting a mortgage from a lender for the whole price, the seller accepts a down payment and lends the buyer the rest. The buyer makes monthly payments to the seller, secured by a promissory note and a mortgage or deed of trust on the property. Many deals amortise the loan over a long term to keep payments affordable but require the remaining balance to be paid in a single balloon payment after a few years, usually by refinancing.
This seller financing calculator works out the monthly payment from the sale price, down payment, interest rate and amortisation period. It shows the amount financed, the balloon due if there is one, and the total interest the seller earns.
How to Use the Seller Financing Calculator
Enter the sale price and the down payment as a percentage.
Enter the interest rate and the amortisation period in years.
Enter the year the balloon is due, or 0 for a fully amortising loan.
The Formulas
loan = price − down payment
payment = loan × r ÷ (1 − (1 + r)^−n)
balloon = loan × (1 + r)^k − payment × ((1 + r)^k − 1) ÷ r
interest = payments made + balloon − loanr is the monthly rate, n the number of months in the amortisation period and k the number of payments made before the balloon.
Step-by-Step Example
A 300,000 sale with 10% down at 7%, amortised over 30 years with a 5-year balloon.
loan 300,000 − 30,000 = 270,000
payment 270,000 × 0.5833% ÷ (1 − 1.005833^−360) = 1,796.32 a month
balloon balance after 60 payments = 254,155.29
interest 60 × 1,796.32 + 254,155.29 − 270,000 = 91,934.30Why Use Seller Financing?
For buyers, seller financing can open the door when banks say no: self-employed buyers with irregular income, buyers rebuilding credit, or properties that do not qualify for conventional loans, such as land, fixer-uppers or mixed-use buildings. Closing is often faster and cheaper. For sellers, offering financing widens the pool of buyers, can support a higher price, and turns the sale proceeds into a stream of interest income. Spreading the gain over several years may also help with taxes under installment sale rules.
Balloon Payments
A 30-year amortisation keeps payments manageable, but few sellers want to wait 30 years for their money. A balloon after three, five or seven years gives the buyer time to improve their credit or build equity and then refinance with a bank to pay off the seller. The risk for the buyer is not being able to refinance when the balloon falls due, because of rates, credit or the property's value. Buyers should plan for that date from the start.
Risks for the Seller
The seller takes on a lender's risks. If the buyer stops paying, the seller must foreclose to recover the property, which takes time and money, and the property may come back in worse condition. A substantial down payment, a credit and income check, proper insurance and a professionally drafted and recorded note and security instrument all reduce the risk. Some sellers use a loan servicing company to collect payments and keep records.
Legal Points
Lending rules apply to many seller-financed sales of homes, including limits on how often a seller can finance sales without a licence and requirements around the buyer's ability to repay. If the seller still has a mortgage, its due-on-sale clause usually lets the lender demand full repayment when the property is sold. Always use a real estate attorney or qualified professional to set up the deal.
Negotiating the Terms
Price, down payment, rate, term and balloon all trade off against each other. A seller may accept a lower rate in return for a higher price or a larger down payment, or a longer balloon in return for a higher rate. Running several combinations through the calculator shows the effect of each on the buyer's payment and the seller's return. Other terms to agree include late fees, who pays property taxes and insurance, whether prepayment is allowed without penalty, and what happens if the property is sold before the balloon.
Interest-Only and Shorter Terms
Some seller-financed deals use interest-only payments for a few years, which lowers the payment but leaves the whole loan due as the balloon. Others amortise over 15 or 20 years with no balloon, giving the seller a steady income and full repayment without the buyer needing to refinance. Set the balloon year to 0 for a fully amortising loan.
Tax Treatment
Sellers who receive payments over more than one year may be able to report the gain as an installment sale, paying tax on each year's share of the gain rather than all at once. Interest received is taxable as ordinary income. A tax adviser can explain how this applies.
Understanding Your Result
The headline gives the monthly payment.
The loan line shows the price, down payment and amount financed.
The balloon line shows the balance due and when.
The seller's return line shows the interest earned and total received.
When Should You Use This Calculator?
Use it when negotiating an owner-financed sale.
Use it to compare different down payments, rates and balloon terms.
Use it to see the payment a buyer could afford.
Common Mistakes
Ignoring the balloon. Plan how it will be paid.
Skipping the paperwork. Use a recorded note and security instrument.
Forgetting the existing mortgage. Due-on-sale clauses apply.
Lending without checks. Verify the buyer's ability to pay.