What an aging report is for
Profit is a story about work done. Cash is a story about money received. An aging report is the bridge between them: it lists what has been invoiced and not yet collected, sorted by how long it has been sitting. Every business that invoices rather than taking payment at the counter has one whether or not anybody writes it down, and the ones that write it down find out about problems earlier.
The single number at the top — total outstanding — is the least interesting thing on the page. The two readings that change decisions are how much of the total has aged past the point where invoices usually get paid, and how much of it belongs to one customer.
Two different reports share one name
Some aging reports bucket by days past due. Others bucket by days since the invoice was issued, ignoring terms entirely. On thirty day terms, an invoice raised forty days ago is ten days past due under the first convention and lands in the 31-to-60 bucket under the second. Both are in normal use, and the same book can look considerably worse or better depending on which one you ran.
The selector on this page lets you produce either, and the printed header says which you chose. That matters when the report leaves your desk. A lender, a bookkeeper or a prospective buyer will read it through whichever convention they are used to, and a report that does not say which basis it used invites them to assume.
Partial payments and why the cents matter
A partially paid invoice keeps its original due date and ages on the remaining balance. That is the standard treatment and it is what happens here: pay half of a February invoice in March and the other half continues aging from the February due date, not from the day of the part payment.
Every figure on this page is carried as an integer number of cents from parsing through to printing. That is not fussiness. An aging report has an arithmetic property people check without thinking: the buckets have to add up to the total outstanding. Carry the amounts as floating point dollars and a report with forty invoices on it will eventually print buckets that sum to a cent away from the total, and the reader who spots it will distrust everything else on the page. The tool prints that check explicitly.
Reading concentration
A book of thirty thousand dollars spread over eight customers and a book of thirty thousand dollars owed by one customer are the same number and completely different situations. The per-customer table is sorted by size for that reason, and the tool says something when a single customer holds more than about two fifths of the balance.
Concentration is not a judgement about anybody. It is a statement about what happens to you if one payment arrives six weeks late. The response is usually not to drop the customer but to know the number, keep some room in the bank against it, and think about whether the terms and the deposit structure on the next job should look different.
Before the invoice exists
Most collection problems are decided before any invoice is raised. Terms that were never agreed in writing, a scope that drifted, no deposit on a long job, and an invoice that arrived without a purchase order reference all produce the same symptom weeks later. The freelance contract guide and the contract form helper deal with the agreement, the quotation maker with what was quoted, the deposit calculator with what to ask for up front, and the invoice maker with the document itself. On construction work where money is held back by arrangement, the retainage cash flow calculator models a lag that is not lateness at all.
Questions people ask
Should I age from the due date or the issue date?
Due date is the more informative of the two for chasing, because it measures lateness rather than elapsed time and it respects the terms you actually agreed. Issue date is simpler and is what some accounting packages default to. The important part is not which you pick but that the report says which it used, because the same invoices can appear in different buckets under each.
Can I charge interest or a late fee on an overdue invoice?
That depends on what your written agreement with the customer says and on your state law, and it is not something this page will suggest a figure for. Charging a fee that was never agreed in advance is a different situation from enforcing one that was. If overdue payment is a recurring problem, the fix is usually in the agreement and the deposit structure rather than in a penalty applied afterwards. Ask a lawyer once and put the answer in your standard terms.
What counts as an old invoice?
It depends on your industry and your customers, which is exactly why the bucket boundaries are fields rather than constants. Thirty, sixty and ninety are the conventional splits and they suit most small businesses on thirty day terms. If you work on longer terms, move the boundaries so that the first bucket represents genuine lateness rather than normal processing time, otherwise every report you produce will look alarming for no reason.
Do I include invoices that are not due yet?
Yes, when you are aging from the due date, and this tool puts them in a "Not yet due" row. Leaving them out gives you a report about lateness rather than a report about what you are owed, and the second one is what tells you whether next month works. When aging from the issue date the distinction disappears, because everything is measured from the same point.
What about an invoice I do not expect to collect?
Leave it on the report while it is still a live claim, and note that fact separately. Deciding that a balance is uncollectible, and how and when that gets written off in your books, is an accounting judgement with tax consequences and it belongs with your bookkeeper or CPA rather than in a bucket on a web page. Quietly deleting the line is the one option that helps nobody, because it removes the record along with the problem.