What DSO means and why it matters
Days Sales Outstanding (DSO) is the average number of days it takes to collect payment after a sale. A DSO of 45 means invoices sit unpaid for six weeks on average. For a service business doing $500K annually, a DSO of 45 vs. a DSO of 20 represents over $34,000 in cash that's stuck in receivables rather than in your bank account.
Most small service businesses have DSOs between 45 and 90 days. The national average for HVAC and plumbing is around 52 days. The best-in-class operators — ones using systematic AR automation — consistently achieve DSO under 25 days on the same customer base.
The fastest single change you can make: add a payment link to every reminder
The data is unambiguous. Invoices with a direct payment link collect 3x faster than invoices that ask customers to call, mail a check, or log into a portal. Friction is the enemy of payment. Every extra step between 'I want to pay this' and 'I paid this' is an opportunity for the customer to get distracted and forget.
Every reminder Surety sends includes a Stripe-powered payment link. The customer clicks, enters their card, and payment posts within seconds. No portal login, no check to mail, no phone call to schedule. This single change — embedded payment links in SMS reminders — reduces DSO by 15-20 days on average.
Timing your follow-up to match how customers actually behave
The optimal reminder timing varies by invoice amount and customer type. For invoices under $1,000: SMS on the due date and again at +7 days typically resolves 70% of overdue accounts. For invoices over $1,000: add a voice call at +14 days, which catches the customers who need a human (or AI) voice to feel a real sense of urgency.
Do not wait until 30 or 45 days to start following up. The first reminder should go out on the day the invoice is due — not as a threat, but as a friendly 'just checking in' with a payment link. Early reminders have dramatically higher response rates than late ones.
Measuring your DSO improvement
Surety's attribution dashboard tracks the most important DSO metric: called vs. uncalled payment velocity. For invoices where Remi contacted the customer, how long did it take to pay? For invoices where no contact was made, how long? The gap between those two numbers is the true value of your AR automation.
Most Surety customers see called invoices resolved 15-25 days faster than uncalled invoices on the same aging schedule. That's your DSO reduction in concrete terms, not a marketing claim.