Accounts payable is the money your business owes to outside suppliers and vendors for goods or services you have already received but have not yet paid for. Those unpaid invoices sit on your balance sheet as a current liability, meaning they are expected to be settled within one year or one operating cycle.1Cornell Law School. Accounts Payable For most businesses, AP is the largest source of short-term credit they use day to day, and how you handle it affects supplier relationships, tax deductions, and IRS compliance all at once.
The arrangement behind AP is called trade credit. When a vendor delivers now and lets you pay later, that is effectively an interest-free loan for a fixed window, usually 30, 60, or 90 days from the invoice date. Miss the window and you can face late fees, loss of credit, or worse.
What Actually Sits in Accounts Payable
AP captures every obligation to an outside party for something your business has already consumed or received. The items split into two broad groups.
On the goods side, the biggest line items are raw materials for manufacturing and inventory bought for resale. Equipment leases and specialized tools purchased on credit terms also land here. On the services side, you will see monthly utility bills, payments to subcontractors, professional consulting fees, and charges for maintenance or security. What ties all of these together is a single trait: someone outside your company gave you something of value, and you still owe them for it.
Payroll owed to your own employees is a different liability and is not part of AP. Long-term debt like a mortgage or a multi-year note also lives elsewhere on the balance sheet.
How an Invoice Moves Through AP
The AP workflow is where most errors and most fraud happen, so the sequence matters.
Three-Way Matching
When a vendor invoice arrives, the finance team does not just cut a check. They run a three-way match, comparing the invoice against the original purchase order (what you asked for) and the receiving report (what actually arrived). All three documents need to agree on quantities, prices, and item descriptions before payment moves forward. When they disagree, the invoice goes back to the vendor for resolution. This one step catches the most common problems: overcharges, short shipments, and invoices for goods that never arrived.
Approval and Payment
Once the match clears, the invoice moves through an internal approval chain. Department managers verify the expense is legitimate and authorized. The accounting system schedules payment based on the credit terms, and payments go out by check, ACH, or wire, each with a unique transaction ID that creates an audit trail.
Avoiding Duplicate Payments
Paying the same invoice twice is one of the most common AP mistakes and easier to do than it sounds. It happens when different departments enter the same invoice with slight variations in the invoice number, or when a vendor sends a reminder that gets processed as a new bill. Keeping one record per vendor in your master file is the best defense, because most accounting software only catches duplicates within the same vendor record. Centralizing AP work with as few people as possible closes the other gap, since decentralized data entry across departments introduces the small inconsistencies that slip past automated controls.
What Happens When AP Goes Unpaid
Missing a payment deadline sets off a predictable chain. The vendor’s first move is usually a formal demand letter. If that does not produce payment, the vendor can file a breach-of-contract lawsuit and seek a court judgment. A judgment creditor can then place liens against your business property or garnish business bank accounts.
In severe cases, creditors can push your company into involuntary bankruptcy. Under federal law, if your business has twelve or more creditors, as few as three of them can file an involuntary petition together as long as their combined unsecured claims meet the statutory minimum, currently $21,050.2Office of the Law Revision Counsel. 11 U.S. Code 303 – Involuntary Cases If your business has fewer than twelve creditors, a single creditor meeting the threshold can file alone.
Internal Controls and AP Fraud
AP fraud is the most expensive type of asset theft businesses face, and the schemes become obvious once you know the pattern.
Segregation of Duties
The core rule is that no single person should control more than one step of the payment process. The employee who enters invoices should not also approve payments, add new vendors to the master file, sign checks, or reconcile the bank account. When one person handles two or more of these, they can create a fictitious vendor, submit fake invoices to it, approve the payments, and cover their tracks in reconciliation. That combination is the most common AP fraud scheme, and it survives wherever duties are not properly separated.
Red Flags to Watch For
Shell company billing is the classic AP fraud: an employee sets up a fake company, submits invoices for goods or services never received, and pockets the payments. Personal purchase schemes work differently. The employee orders personal items on the company’s account, sometimes returning the goods later for a cash refund.
Warning signs that warrant a closer look include:
- Invoices with vague descriptions like “consulting services” and no clear deliverables
- Vendor addresses that match an employee’s home address, or vendors with only a P.O. box
- Rapidly increasing purchases from a single vendor, or large amounts broken into smaller invoices that each fall below approval thresholds
- Company names consisting only of initials, or vendors no one in operations recognizes
The single biggest control failure behind these schemes is letting the person who processes payments also approve new vendors. If nothing else changes, change that.
How AP Shows Up on the Books
Journal Entries
AP uses double-entry bookkeeping. When your business receives an invoice, the accountant credits the accounts payable account (increasing the liability) and debits the corresponding expense or asset account. When the bill gets paid, the entry reverses: a debit to accounts payable reduces the liability and a credit to cash records the outflow. Every invoice and every payment produces this paired entry, which is what keeps the books balanced.
Aging Reports
An aging report sorts every unpaid invoice into time buckets: current, 1–30 days past due, 31–60 days, 61–90 days, and over 90 days. The report shows which payments are approaching their deadlines and which are already overdue. Invoices sitting in the 90-plus day column are where relationships start to break. Vendors in that bucket are the ones most likely to cut off your credit, hand you to a collection agency, or sue.
Days Payable Outstanding
Days payable outstanding, or DPO, converts your AP balance into calendar days. The formula is average accounts payable divided by cost of goods sold, multiplied by 365. A DPO of 45 means you are averaging about six weeks between receiving an invoice and paying it. Businesses with strong bargaining power over their suppliers tend to have higher DPOs because they can negotiate longer payment windows without consequence. A rising DPO can reflect either smart cash management or trouble paying bills on time, and the aging report is what tells you which.
When AP Expenses Become Tax Deductions
The timing of your deduction for an AP expense depends on whether your business uses the cash method or the accrual method of accounting.
Under the cash method, you deduct expenses in the tax year you actually pay them. An invoice sitting in your AP ledger on December 31 is not deductible yet, no matter when the goods arrived. The deduction lands when the check clears or the ACH transfer settles.3Internal Revenue Service. Publication 538 – Accounting Periods and Methods
Under the accrual method, the deduction happens earlier. You can deduct a business expense once two conditions are met: all events that fix the liability have occurred (meaning you know you owe the money and can determine how much), and economic performance has taken place, which generally means the goods were delivered or the services were performed. There is a useful exception for recurring items. If the all-events test is met by year-end and economic performance happens within 8½ months after the close of the year, you can still treat the expense as incurred in the earlier tax year.3Internal Revenue Service. Publication 538 – Accounting Periods and Methods
One trap: if you owe money to a related person (for example, paying a family member’s LLC for services) and that person uses the cash method, you cannot deduct the expense until you actually make the payment and the recipient includes it in income.3Internal Revenue Service. Publication 538 – Accounting Periods and Methods The IRS will not let you book the deduction on an accrual basis while the related party defers reporting the income.
1099-NEC Reporting From AP Records
Your AP records are the starting point for a significant IRS compliance obligation: filing information returns for payments to non-employees.
The 2026 Threshold
For tax year 2026, if your business pays $2,000 or more to a non-employee for services, you must report those payments on Form 1099-NEC. That threshold rose from $600 in prior years and will be adjusted for inflation starting in 2027.4IRS.gov. Publication 1099 General Instructions for Certain Information Returns – For Use in Preparing 2026 Returns Common examples include fees paid to subcontractors, independent consultants, freelancers, and board directors.
Filing Deadlines for 2026 Payments
- January 31, 2027: furnish Copy B of Form 1099-NEC to the recipient
- February 28, 2027: file Copy A with the IRS on paper
- March 31, 2027: file Copy A with the IRS electronically
If any deadline falls on a weekend or federal holiday, it shifts to the next business day.4IRS.gov. Publication 1099 General Instructions for Certain Information Returns – For Use in Preparing 2026 Returns
Penalties for Late or Missing Filings
The IRS imposes per-form penalties for failing to file correct information returns, and the amount grows the longer you wait. The penalty is lowest if you correct the filing within 30 days of the deadline, higher if you correct it by August 1, and highest if you file after August 1 or never file at all. Intentional disregard carries the steepest penalty and has no maximum cap. Small businesses with average annual gross receipts of $5 million or less get lower maximum caps at each tier.5Office of the Law Revision Counsel. 26 U.S. Code 6721 – Failure to File Correct Information Returns The dollar figures are adjusted for inflation each year.
Backup Withholding
Before paying a vendor for the first time, collect a completed Form W-9 to get their taxpayer identification number. If a vendor refuses to provide a TIN or gives an incorrect one, you are required to withhold 24% of every reportable payment and deposit it with the IRS.6IRS.gov. Instructions for the Requester of Form W-9 Skip the withholding and your business becomes liable for the uncollected amount. This obligation catches businesses off guard because it turns a routine AP function into a tax collection duty.
Early Payment Discounts
Many vendors offer a discount for paying before the full term expires. The most common arrangement is written as “2/10 net 30,” which means you get a 2% discount if you pay within 10 days, otherwise the full amount is due in 30 days. A 2% discount for paying 20 days early may not sound like much, but annualized it works out to roughly 36%. That makes early payment one of the highest-return uses of spare cash available to most businesses.
The strategic question is whether to pay early and capture the discount or hold the cash longer and use the full credit period. Businesses with tight cash flow often cannot take the discount even when the math favors it. Your AP aging report and DPO give you the data to answer that vendor by vendor, instead of applying one blanket rule to a payables list that never fits it.