What is accounts payable?
Accounts payable represents money a business owes to vendors, suppliers, and creditors for purchases made on credit — goods received, services rendered, or expenses incurred but not yet paid in cash. It is a current liability on the balance sheet because it is expected to be settled within the normal operating cycle (typically within 30–90 days).
Three things AP is not:
- Not debt — AP arises from trade credit, not borrowing. There is no interest unless payment terms are breached.
- Not an accrual — AP is a confirmed obligation with an invoice. Accrued liabilities are estimates of obligations not yet invoiced.
- Not accounts receivable (AR) — AP is what you owe others. AR is what others owe you. They are mirror images from opposite sides of the same transaction.
Managing AP well means taking full advantage of supplier payment terms without damaging relationships or incurring late fees — maximising the free cash float that trade credit provides.
Accounts payable formula — the roll-forward method
The most important AP formula used in accounting and financial modelling is the roll-forward — it tracks how AP changes across a period:
Here is a concrete monthly example — a retail supplier relationship:
AP increased by $5,000 this month — the business received more new invoices than it paid out. This is normal during a growth phase or when taking on new supplier relationships.
Deriving AP from balance sheet data
If you have comparative balance sheets, AP is already calculated and disclosed directly. The change in AP from one period to the next appears in the cash flow statement under operating activities:
Negative ΔAP = AP decreased = cash outflow (paid more than incurred)
Where accounts payable sits on the balance sheet
AP is always a current liability — it sits under liabilities, not assets. It is typically the largest single line item in current liabilities for product-based and manufacturing businesses.
Note the relationship between AP (a liability) and inventory or COGS (expenses/assets). When a business buys inventory on credit: Inventory ↑ on assets side, AP ↑ on liabilities side. When it pays the supplier: Cash ↓, AP ↓. The balance sheet always stays balanced.
Step-by-step calculation
AP turnover ratio and days payable outstanding (DPO)
Knowing the closing AP balance is useful, but converting it into a ratio makes it comparable across periods and companies of different sizes. Two ratios matter most:
Average AP = (Opening AP + Closing AP) ÷ 2
Higher = paying suppliers faster
or: Average AP ÷ (COGS ÷ 365)
Average days taken to pay each invoice
What is a healthy DPO?
There is no universal "good" DPO — it depends heavily on industry, business model, and supplier terms. The most useful benchmark is comparing your DPO against the payment terms you have negotiated:
A DPO significantly below your payment terms means you are paying early — potentially forgoing interest-free cash float. A DPO significantly above terms means you are paying late — risking supplier relationship damage or early payment discount forfeiture. The optimal DPO sits just inside the credit terms you have negotiated.
Accounts payable vs accounts receivable
AP and AR are mirror images of each other — the same trade credit transaction creates AP for the buyer and AR for the seller:
Money owed by the business to suppliers. Current liability on your balance sheet. Created when you buy on credit. Settled when you pay the invoice. Managing AP well = maximising free cash float within payment terms.
Money owed to the business by customers. Current asset on your balance sheet. Created when you sell on credit. Settled when the customer pays. Managing AR well = collecting quickly to maintain cash flow.
The cash conversion cycle (CCC) connects both: CCC = Days Inventory Outstanding + Days Sales Outstanding − Days Payable Outstanding. A shorter CCC means faster conversion of operations to cash. Increasing DPO (paying later) directly shortens the CCC and improves working capital — which is why large businesses negotiate extended payment terms aggressively.
Worked examples
Retail shop — month-end AP
Opening AP $12,000 · Purchases $28,500 · Payments $25,200
✅ Closing AP = $15,300 · AP sub-ledger should match
Factory — AP turnover & DPO
Q1 COGS $480,000 · Opening AP $52,000 · Closing AP $68,000
🔵 45.6-day DPO — within 45-day net terms
AP change in operating cash flow
Opening AP $38,000 · Closing AP $43,000
✅ AP increase = operating cash inflow
Returns reduce AP balance
Opening AP $22,000 · Purchases $35,000 · Returns $4,200 · Payments $31,000
🟡 Returns reduce AP like payments do
Common mistakes to avoid
- Mixing cash purchases with credit purchases. Only invoices on credit terms create AP. A cash purchase paid immediately at point of delivery never enters the AP balance — it goes directly to cash and expense or inventory.
- Confusing AP with accrued liabilities. AP requires a specific invoice from a supplier. Accrued liabilities are estimated obligations where no invoice has yet been received — for example, estimated wages payable or accrued utilities. They sit on separate balance sheet lines.
- Forgetting credit notes and purchase returns. When goods are returned or a supplier issues a credit note, AP decreases. These must be recorded in the same way as payments — as deductions from the AP balance.
- Using COGS instead of purchases in AP turnover. Technically, AP turnover should use net credit purchases in the numerator, not COGS. COGS excludes beginning inventory and includes ending inventory, making it an imperfect proxy. Where only COGS is available (as in many financial analysis contexts), it is an acceptable approximation.
- Treating a rising AP as always negative. Increasing AP can mean the business is growing — buying more inventory to meet demand — or it can signal cash flow problems. Always read AP movement alongside revenue growth, DPO trends, and cash balance before drawing conclusions.
Frequently asked questions
What is the formula for accounts payable?
Closing AP = Opening AP + Credit purchases during the period − Cash payments to suppliers during the period. This is the roll-forward method used in accounting, financial modelling, and AP sub-ledger reconciliation.
Is accounts payable a debit or credit?
AP has a normal credit balance. When AP is created (goods received on credit), you credit AP. When AP is paid (cash goes to supplier), you debit AP. This is consistent with the accounting rule that liabilities carry credit balances.
What is the difference between accounts payable and accrued expenses?
Accounts payable represents confirmed obligations backed by a specific supplier invoice. Accrued expenses (or accrued liabilities) are estimated obligations for goods or services received but for which no invoice has been received yet — for example, wages earned but not yet paid, or utilities used but not yet billed. Both are current liabilities, but they sit on separate lines.
Does an increase in accounts payable mean the company is in trouble?
Not necessarily. Rising AP can mean the business is growing and purchasing more on credit — which is normal and healthy during expansion. It becomes a concern if AP is rising faster than revenue, DPO is significantly exceeding supplier terms, or the business is showing declining cash balances alongside rising AP — which can signal inability to pay suppliers.
How does accounts payable affect cash flow?
In the cash flow statement under operating activities, an increase in AP is added back (it is a source of cash — you incurred expenses but kept the cash). A decrease in AP is subtracted (you paid out more than you incurred — a use of cash). AP is one of the key working capital items that bridges net income and operating cash flow.