The terms, defined once
Receivables vocabulary is small and most of it is used loosely. These are the five words that actually appear on the invoices and in the software.
- Days sales outstanding
- The average number of days between issuing an invoice and being paid for it. Calculated as accounts receivable divided by revenue, multiplied by the number of days in the period.
- Net terms
- The number of days after the invoice date on which payment is due. Net 30 means due thirty days after issue, not thirty days after the work finished, which is a distinction clients will sometimes exploit.
- Ageing
- A breakdown of what is owed by how overdue it is, usually in buckets: current, 1–30 days, 31–60, 61–90, over 90. For a small business the ageing list is far more useful than any average, because it names the specific invoices.
- Best possible DSO
- What your DSO would be if every client paid exactly on terms. It is your terms, weighted by invoice value. The gap between this and your real DSO is the number worth watching.
- Statutory interest
- Interest on a late commercial debt that applies by law rather than by contract, in the jurisdictions that provide it. Rates and rules vary by country; there is a calculator on the late fee page but not legal advice.
- Bad debt
- Money you have decided you will not be paid. Most freelancers never formally recognise it, which is why the true cost of late payment is invisible in their own numbers.
Also called: DSO · average collection period
See also: Ageing, Net terms
Also called: Net 14 · Net 30
The formula, and its problem
Why the number misbehaves at small volume
DSO is (accounts receivable ÷ revenue) × days in period. Over a quarter with $30,000 of revenue and $9,000 outstanding, that is 90 × 9,000 ÷ 30,000, or 27 days. Straightforward.
The problem is variance. A finance team calculating DSO across four hundred invoices is measuring a population; the number moves slowly and a change means something. A freelancer calculating it across nine invoices is measuring a handful of individual decisions, and a single $8,000 client who pays a fortnight late can swing the figure by twenty days on its own. You will read that swing as a trend, adjust something, and learn nothing.
There is a second failure that is less obvious. DSO is sensitive to when you invoice, not just when you are paid. Bill everything on the last day of the quarter and your DSO looks terrible; bill the same work on the first day and it looks excellent. Nothing about the client's behaviour changed.
The same quarter, calculated four ways
One real pattern of invoices, measured with the four metrics people reach for. Notice how much they disagree.
| Measure | Value | What it is really telling you |
|---|---|---|
| DSO | 27 days | Dominated by the largest open invoice |
| Median days to pay | 9 days | Most clients pay quickly and the average hides it |
| Worst invoice age | 63 days | The only number that names a problem you can act on |
| Share of invoices paid on terms | 72% | The most stable of the four at this volume |
Source: A single freelance quarter: nine invoices, $30,400 billed, $9,100 outstanding at close. Illustrative, not a benchmark.
If you only track one, track the last one. It is a proportion rather than an average, so a single large invoice cannot dominate it, and it moves for reasons you can name.
What to actually watch, in order of usefulness
- The oldest unpaid invoice, by nameOne number, one client, one action. It is the entire receivables report a business of one needs.
- Share of invoices paid within terms, over the last twentyA rolling proportion. Stable enough to notice when it moves, specific enough to act on.
- Which clients are repeatedly in the 30–60 bucketPattern, not incident. This is the list that should inform your deposit policy, not your reminder schedule.
- Total outstanding against one month of costsThe only genuinely urgent number. If outstanding is less than a month of costs, late payment is an annoyance; if it is three months, it is the business.
- DSO, quarterly, and only over a year of historyUseful for spotting a slow drift. Useless month to month.
Anything a chasing tool shows you beyond this list at freelance scale is decoration.