Accounts payable and notes payable are both money your business owes, but they behave like different animals. Accounts payable is the informal tab you run with suppliers when you buy on credit during normal operations. Notes payable is a formal debt backed by a signed promissory note that spells out the principal, the interest rate, and the repayment schedule. One is a byproduct of doing business; the other is a deliberate financing decision.
The differences matter because each obligation costs you differently, sits on your balance sheet differently, and creates very different problems if you fall behind.
The Core Differences
Documentation
Accounts payable relies on a vendor invoice and whatever informal credit understanding exists between buyer and seller. That’s it. Notes payable requires a signed promissory note, a standalone legal contract that specifies every material term of the debt. A lender can enforce a promissory note in court without needing to prove the underlying transaction that led to the loan.
Interest
AP is generally interest-free as long as you pay within the agreed terms. Miss a discount window and you lose the discount, but interest doesn’t accrue the way it does on a loan. Notes payable nearly always carry an explicit interest rate. Even when a note is issued at zero interest or a below-market rate, the IRS may impute interest anyway, treating the arrangement as if the borrower received a discounted loan amount and owes original issue discount over the life of the note.1Office of the Law Revision Counsel. 26 U.S. Code 7872 – Treatment of Loans With Below-Market Interest Rates
Payment Terms and Maturity
Accounts payable is strictly short-term. Invoices typically state “Net 30” or “Net 60,” meaning the full amount is due within 30 or 60 days. Some vendors offer early-payment discounts written as “2/10 Net 30,” which means 2% off if you pay within 10 days, otherwise full balance in 30. AP almost always settles within 30 to 90 days.
Notes payable is more flexible. A promissory note can mature in 90 days or stretch out ten years or longer, depending on the purpose of the loan.
Collateral
Trade payables are almost always unsecured. Your supplier is extending credit based on your payment history and reputation, not a legal claim to specific assets. Nobody puts a lien on your equipment because you ordered printer paper.
Notes payable, especially for larger or longer-term loans, frequently require collateral. The lender may take a security interest in the equipment being financed, in inventory, or in other business assets. Filing that security interest with the state typically costs between $5 and $40. If you default on a secured note, the lender can seize the pledged collateral to recover the balance.2United States Bankruptcy Court. How Do I Know if a Debt Is Secured, Unsecured, Priority, or Administrative?
How Each One Sits on the Balance Sheet
Because AP is tied to the normal operating cycle, it’s always classified as a current liability. That means it flows directly into your current ratio (current assets divided by current liabilities) and your quick ratio. A company stretching its payables to conserve cash will show a lower current ratio, which lenders and investors read as a liquidity concern.
Notes payable has a split personality. A 90-day note for a small equipment purchase is a current liability. A five-year bank loan gets divided: the principal due within the next 12 months sits under current liabilities, and the remaining balance goes under non-current liabilities. Any debt scheduled to mature within one year (or the operating cycle, if longer) after the balance sheet date counts as current.
The accounting mechanics also differ. Recording AP is straightforward: debit an expense or asset account, credit accounts payable. When you pay, you debit AP and credit cash. Notes payable is more work, because every payment splits into a principal portion and an interest expense portion, and your books need to reflect that separation across the life of the note.
When Accounts Payable Turns Into Notes Payable
Sometimes a business can’t cover a large supplier invoice on time. Rather than let the relationship fall apart, the buyer and supplier may agree to convert the overdue balance into a formal promissory note. The journal entry debits accounts payable, removing the obligation from the AP ledger, and credits notes payable, creating a new formal obligation.
Both sides get something. The buyer gets extended payment terms and avoids an immediate cash crunch. The supplier gets a legally enforceable document with a stated interest rate, which is worth more than an aging receivable that might never get paid. The buyer’s trade-off: what was interest-free trade credit now carries an interest cost and legally binding terms.
Businesses also use this move strategically. If a company needs cash on hand for a growth opportunity, it can negotiate with a key supplier to formalize outstanding invoices into a note, spreading payments across months or years while freeing up working capital.
What Happens If You Don’t Pay
The consequences of falling behind look completely different depending on which obligation you’ve missed.
Late Accounts Payable
Paying AP late won’t trigger a lawsuit overnight, but the damage is real. You lose early-payment discounts, and across hundreds of invoices a year that adds up quietly. Suppliers may shorten your terms, demand cash on delivery, or stop prioritizing your orders when supply gets tight. A reputation as a slow payer travels fast through supplier networks and can lock you out of the best vendors and pricing.
Default on Notes Payable
A promissory note default is immediate and legally consequential. Most notes include an acceleration clause, which lets the lender demand the entire remaining principal at once if you miss a payment or breach another term. The lender doesn’t have to invoke this right automatically, and borrowers who cure the default before the lender accelerates the loan can sometimes avoid the worst outcome.3Legal Information Institute. Acceleration Clause Once acceleration happens, though, you owe everything immediately, plus accrued interest.
Many promissory notes also include debt covenants that restrict what the borrower can do. Common covenants require maintaining a minimum debt-to-equity ratio, limit additional borrowing, or restrict dividend payments. Violating a covenant, even without missing a payment, can trigger penalties ranging from a higher interest rate to full loan acceleration. If the note is secured, the lender can also take the collateral.
Tax Treatment
When you pay an accounts payable invoice, you’re typically deducting a business expense: cost of goods sold, an operating expense, or part of an asset’s cost basis. The payment itself isn’t a taxable event. If a creditor forgives an AP balance, however, the canceled amount generally counts as taxable income in the year the cancellation occurs.4Internal Revenue Service. Topic No. 431, Canceled Debt – Is It Taxable or Not?
Notes payable adds interest expense to the picture. Business interest is generally deductible, but Section 163(j) of the Internal Revenue Code caps the deduction for larger businesses. The limit is the sum of business interest income, 30% of adjusted taxable income, and any floor plan financing interest. Small businesses meeting the gross receipts test are exempt from this cap. For tax years beginning after December 31, 2024, legislation amended the calculation to let taxpayers add back depreciation and amortization deductions when computing adjusted taxable income, effectively restoring the more favorable EBITDA-based formula.5Internal Revenue Service. Questions and Answers About the Limitation on the Deduction for Business Interest Expense
Below-market or zero-interest notes between related parties raise a subtler issue. Under 26 U.S.C. ยง 7872, the IRS treats these as if the lender transferred a gift or compensation equal to the forgone interest, and the borrower retransferred that amount back as interest. In practice, the IRS calculates what the interest should have been using the applicable federal rate and taxes both parties accordingly, even though no interest actually changed hands.1Office of the Law Revision Counsel. 26 U.S. Code 7872 – Treatment of Loans With Below-Market Interest Rates
Which One to Watch More Closely
Accounts payable is the liability you interact with daily; notes payable is the one you negotiate carefully and then manage on a fixed schedule. The practical trap is that AP mismanagement sneaks up on you. Nobody sends a demand letter because you paid an invoice five days late, but lost discounts, strained supplier relationships, and tightened credit terms can quietly rival the cost of a formal loan.
Notes payable demands a different discipline: tracking covenant compliance, allocating each payment correctly between principal and interest, and holding enough liquidity to keep an acceleration clause from ever getting pulled. Both matter. They just fail differently.