An open invoice is a bill a seller has issued to a buyer that hasn’t been paid in full yet. From the moment it’s sent until the balance reaches zero, it stays “open” on both companies’ books: an asset the seller expects to collect, and a liability the buyer owes. How long an invoice stays open, and how you track and handle it, shapes your cash flow, your tax bill, and even what your business is worth if you ever sell it.
What Keeps an Invoice Open
The “open” status attaches the moment the seller issues the invoice and persists until the balance is fully settled. An invoice still within its payment window, whether Net 15, Net 30, or Net 60, is open. An invoice the buyer has partially paid is open. The only things that close it are full payment, a formally applied credit memo, or a negotiated write-off.
One point of confusion worth clearing up: a pro forma invoice is not an open invoice. A pro forma is an estimate sent before goods ship or services are delivered. No sale has happened, so no receivable or payable exists. An invoice becomes open only after the transaction is complete and a final invoice goes out requesting actual payment.
Where an Open Invoice Lives on the Books
The accounting treatment depends on which side of the transaction you’re on. For the seller, an open invoice is a current asset recorded under Accounts Receivable. The AR balance is the combined value of every unpaid invoice the business has issued. Under accrual accounting, the seller also records the revenue on the income statement at the time of sale, before any cash actually arrives.
For the buyer, the same invoice is a current liability under Accounts Payable. The AP balance aggregates every invoice the business has received but not yet paid. When payment finally moves, both ledgers update at once: the seller reduces Accounts Receivable, the buyer reduces Accounts Payable, and cash shifts from one side to the other. That double-entry recording keeps both companies’ financial statements balanced and consistent with generally accepted accounting principles.
What an Open Invoice Means for Your Taxes
Whether an open invoice creates a tax obligation before the money arrives depends entirely on your accounting method. Under the accrual method, you report income in the year you earn it, no matter when payment lands. Deliver goods in December and send an invoice, and that revenue counts for the current tax year even if the check doesn’t clear until February.
Under the cash method, you report income only when you actually receive payment. The same December delivery wouldn’t produce taxable income until the following year. For a business carrying a large receivable balance at year-end, that timing difference can be substantial.
Not every business can choose freely. The IRS generally requires corporations and partnerships to use accrual accounting unless their average annual gross receipts over the prior three tax years fall below an inflation-adjusted threshold.1Office of the Law Revision Counsel. 26 USC 448 – Limitation on Use of Cash Method of Accounting The current figure is published each year in IRS revenue procedures.2Internal Revenue Service. Publication 538 – Accounting Periods and Methods
Your method also controls whether you can deduct an unpaid invoice as a bad debt. An accrual-method business has already reported the income from the sale, so it has met the threshold requirement for a bad debt deduction once the invoice becomes uncollectible. A cash-method business generally cannot deduct an unpaid invoice, because it never reported the income to begin with.3Internal Revenue Service. Topic No. 453 – Bad Debt Deduction
Tracking What’s Still Open
The main tool for managing open invoices is the accounts receivable aging report. It sorts every unpaid invoice into buckets based on how long it’s been outstanding: current (not yet due), 1–30 days past due, 31–60 days past due, 61–90 days past due, and over 90 days past due.
The point of the categorization is prioritization. An invoice five days past due probably needs a reminder email. One at 75 days past due may need a phone call from a manager. One at 120 days past due may need a collections agency or a write-off decision. The older the invoice, the less likely you are to collect it, and the aging report puts that risk in front of you.
Finance teams also use aging data to estimate future losses through an allowance for doubtful accounts. The method is simple: look at historical collection rates for each aging bucket and apply those percentages to current balances. If 2% of invoices in your 31–60 day bucket historically go unpaid, and you have $200,000 sitting there, you’d reserve $4,000 against potential losses. That reserve appears on the balance sheet as a reduction to accounts receivable.
Days Sales Outstanding (DSO) is the other number worth watching. Divide total accounts receivable by total credit sales for a period, then multiply by the number of days in that period. A DSO of 45 means it takes your business an average of 45 days to collect after a sale. In many industries, a DSO between 30 and 45 days is considered healthy. A rising DSO means invoices are staying open longer, which can squeeze cash flow even when sales look strong.
When Buyers Dispute or Short-Pay
Not every open invoice stays open because the buyer is slow. Some are formally disputed, and some get paid for less than the full amount on purpose. Both situations call for a different response than standard collections.
When a buyer disputes an invoice, the practical first move is to pause collection activity on the disputed amount. Automated reminders during an active dispute damage the relationship and rarely speed things up. If only part of the invoice is contested, collect the undisputed portion and work the rest separately. If the dispute uncovers a real error, such as a wrong quantity, incorrect pricing, or a duplicate bill, issue a credit memo against the original and send a corrected invoice. The original stays in the system marked as superseded. If the invoice turns out to be accurate, document that with signed delivery receipts or contract terms and resume collection.
Short payments are harder. Some buyers deliberately pay less than invoiced, counting on the seller to absorb the difference rather than chase a small shortfall. Across dozens or hundreds of invoices, that practice eats into margins. The accounting team needs to flag every short payment, investigate whether there’s a legitimate reason like damaged goods or a pricing disagreement, and either collect the remainder or formally write off the difference. Unexplained shortfalls left as partially open invoices clutter the receivable ledger and distort cash flow projections.
When an Open Invoice Won’t Be Paid
At some point an open invoice moves from “late” to “never going to be paid.” Recognizing that transition matters for both your books and your tax return.
On the accounting side, businesses generally use one of two methods. The allowance method, described above, estimates losses in advance and reserves against them; a specific invoice written off later is applied against that existing reserve instead of hitting the current period’s expenses. The direct write-off method skips the reserve and records the loss only when an invoice is confirmed uncollectible. The direct method is simpler but less accurate, because the expense lands in a different period than the original sale. For any business where bad debts are more than trivial, the allowance method is what GAAP expects.
On the tax side, the IRS allows businesses to deduct bad debts, but you have to show the debt is genuinely worthless. That means evidence you’ve taken reasonable collection steps and that there’s no realistic expectation of payment. You don’t have to sue first or wait until the debt comes due, but you do need to document that collection has failed.3Internal Revenue Service. Topic No. 453 – Bad Debt Deduction Business bad debts, which include unpaid credit sales, can be deducted in full or in part, and the deduction has to be taken in the year the debt becomes worthless.4Office of the Law Revision Counsel. 26 USC 166 – Bad Debts
There’s also a legal deadline on your ability to sue for payment. Every state sets its own statute of limitations for debt collection, with the range across the country running from three to ten years depending on the state and the type of debt. Once that window closes, the debt is time-barred, and federal regulations prohibit debt collectors from suing or threatening to sue to collect it.5eCFR. 12 CFR 1006.26 – Collection of Time-Barred Debts The debt still exists in a technical sense, and the buyer still owes the money, but your legal enforcement options are gone. For invoices nearing the limit in your state, the decision to write off or escalate needs to happen well before the deadline hits.
What Open Invoices Do to Your Business’s Value
If you ever sell your business or raise outside capital, your open invoices will be examined closely. Accounts receivable is often one of the largest current assets on a small business balance sheet, and buyers and investors don’t accept the book value at face.
Age and collectibility drive the analysis. Receivables that are current or only recently past due are generally valued close to their face amount. Invoices open 90 days or more are often discounted 20–30% in a valuation, reflecting the reduced odds of collection. A business that collects most invoices within terms will command a higher price than one with a bloated, aging ledger, even when both report the same revenue.
Collection efficiency also shows up in the AR turnover ratio, which measures how many times per year the business converts its receivables into cash. Healthy businesses typically turn receivables 7–12 times annually. A ratio well below your industry average tells a buyer that cash is tied up in unpaid invoices, which raises the working capital the new owner will need to fund operations.