Days Sales Outstanding (DSO)

How DSO is calculated

Standard formula: DSO = (Accounts Receivable / Total Credit Sales) × Number of Days in Period. For a service business with \$120,000 of AR and \$60,000/month of credit sales, monthly DSO is (120,000 / 60,000) × 30 = 60 days.

Variants exist: 'best possible DSO' uses only current (not yet due) receivables; 'countback' DSO walks backward through actual invoices to find the day count. For owner-operator forecasting the simple formula is fine; for benchmarking against peers you want to use the same variant they use.

Why DSO matters more than owners think

A 10-day improvement in DSO on \$1M of annual revenue releases roughly \$27,000 of cash permanently. That's not 'extra' cash — it's cash that was always yours, just trapped in customer hands. Many service businesses can compress DSO by 5-15 days through better invoicing, deposits, or simple weekly collections calls.

Public companies report median DSO around 45-55 days; service-business owners commonly run 50-70 days. If your DSO exceeds your stated payment terms by more than 10-15 days, the gap is usually slow invoicing on your side, not slow paying on the customer's.

What drives DSO and what to do about it

DSO is the joint output of three things: the payment terms you offer (net-15, net-30, net-60), how compliant customers are with those terms, and how disciplined your collections process is. A high DSO can come from any combination — terms that are too generous, customers that pay late, or no one chasing the late ones. The fix depends on which is the binding constraint.

Segment DSO by customer to find concentration risk. If 80% of your DSO is driven by your top three customers, you have a relationship problem more than a process problem. Often a candid conversation with a CFO counterpart at a slow-paying customer ('your treasury is using our cash; can we move you to net-15 with a small discount?') solves more than another round of dunning emails.

DSO can be artificially low if you write off bad debt aggressively or factor receivables. When benchmarking, compare DSO on a consistent basis — gross AR ÷ daily sales — and pair it with bad-debt expense as a % of revenue. A company with 25-day DSO but 4% bad debt is not actually managing receivables well; they're just losing the slow ones.