Days sales outstanding (DSO) is accounts receivable divided by credit sales for a period, multiplied by the number of days in that period. Calculate it the same way every month, split it into the days you control and the days you don't, and set a target on the controllable part. Each day you remove is worth roughly one day of credit sales in cash.
Step 1: Calculate DSO the same way every month
The standard formula is:
DSO = (accounts receivable / total credit sales) x number of days
Use credit sales only, not cash sales. Use the same period length and the same receivables figure (period-end or average) every time, or your trend will move for reasons that have nothing to do with collections.
If your sales are seasonal or lumpy, consider the countback method. It starts with ending receivables and counts back through daily credit sales until the balance is covered, which ties DSO to actual recent sales rather than an annual average.
Step 2: Split DSO into its drivers
A single DSO number hides three different problems:
- Terms. If your standard terms are net 45, DSO will not go below about 45 without changing terms.
- Billing delay. Days between delivery and a correct invoice reaching the customer.
- Collection delay. Days past due, driven by disputes, errors and follow-up.
Measure billing delay and days past due separately. They are usually where the fixable days are.
Step 3: Find the days you control
Look for the operational causes:
- Invoices sent late because order data had to be re-keyed
- Invoices rejected because the PO number or price did not match
- Disputes that sit unanswered
- Overdue accounts that are not followed up until they are 60 days late
Each of these is a process problem, not a customer problem, and each has a measurable number of days attached.
Step 4: Put a value on each day
One day of DSO is roughly one day of credit sales. At $120 million of annual credit sales, that is about $329,000. A 10-day reduction releases about $3.3 million of cash once, and saves the cost of financing it every year after.
Be clear about which value you mean. The one-off cash release and the ongoing financing saving are both real, but they are different numbers.
Step 5: Set the target and the measure
Set the target on the controllable days, not the headline. For example: cut billing delay from 4 days to 1 and average days past due from 17 to 10. Agree the method, the data source and the baseline month before you start, and report the drivers every month alongside DSO.
Where AI agents fit
Billing delay and collection follow-up are mostly routine work: entering orders, matching invoices and chasing overdue accounts on a schedule. Our finance operations service runs that work with agents, measures DSO against a baseline pulled from your own systems, and prices part of the service as a share of the verified improvement. See how to set a baseline for gain-share pricing.