Understand DSO metric, why it matters for cash flow, and tactics to reduce it and collect faster.
You invoice a customer for $50K on January 1. They don't pay until February 15.
That's 45 days. During those 45 days, you don't have the cash. You still have to pay your team. You still have to pay rent.
If your customers typically take 45 days to pay (your DSO), and you have $1M in revenue per month, you're always waiting for $1.5M in invoiced but unpaid revenue. That's cash that could be in your bank account earning interest or funding growth.
This metric is called DSO—Days Sales Outstanding. And it's one of the most important metrics for cash flow health.
What Is DSO?
DSO is the average number of days it takes a customer to pay their invoice.
DSO = (Accounts Receivable / Revenue) × Number of Days
Revenue (this month) = $200K
DSO = ($500K / $200K) × 30 = 75 days
This means it takes an average of 75 days for customers to pay.
Why DSO Matters
If your DSO is 60 days and your monthly revenue is $200K, you're waiting on $400K of unpaid invoices at any given time.
That $400K is yours (you've already delivered the product/service), but you can't spend it because customers haven't paid.
Working capital requirement
Lower DSO = less cash trapped waiting for payments = more cash available for operations, growth, and emergencies.
Survival for startups
A growing startup can be cash-strapped while growing revenue. Why? Because DSO is killing them.
- January: $50K revenue, $25K collected. Cash: +$25K
- February: $100K revenue (growth!), but only $50K collected. Cash: +$50K (but waiting on $50K from Jan)
- March: $150K revenue, $100K collected. Waiting on $100K from Feb, $75K from March.
By month 3, you've generated $300K in revenue but only collected $175K. You're down $125K in working capital, even though business is growing.
If you run out of cash before collecting payments, you might have to lay off people or shut down. This is called a cash flow crisis, and it's real.
Competitive advantage
Companies with low DSO have more cash to invest in growth, marketing, R&D. Companies with high DSO are cash-strapped.
Industry Benchmarks for DSO
Government contractors often wait 90+ days for payment (just how government works). B2C e-commerce is fast (credit card processes immediately).
How to Improve Your DSO
1. Set clear payment terms upfront
Your invoice should say: "Due within 30 days of invoice date."
If you don't specify, customers assume net 90 or net whatever they want.
Strategy: Most B2B uses net 30 (due within 30 days). Some use net 15 (faster collection). Net 60 or net 90 should be rare (only for large enterprise contracts).
2. Make invoices clear and easy to pay
Your invoice should include:
- Your company name and address
- Customer name and address
- Invoice number (unique identifier)
- Invoice date
- Due date (clearly stated)
- Itemized services/products
- Total amount due
- Payment instructions (where to pay, bank info, ACH details, credit card link)
- Any early payment discount ("Pay within 10 days, get 2% discount")
Why: Unclear invoices delay payment. Customers can't find where to send payment.
3. Send invoices immediately
Invoice should be sent the day you deliver the service or product, not days later.
Benefit: Payment clock starts ticking immediately. If net 30, payment due in 30 days vs. 35 days if you wait 5 days to send.
4. Follow up on overdue invoices
Invoice is due January 15. January 20, it's not paid. You should follow up.
- Day of due date: Send invoice reminder
- 5 days overdue: Send friendly follow-up email
- 10 days overdue: Phone call
- 20 days overdue: Escalate (might be a problem)
- 30 days overdue: Legal/collections might be needed
5. Incentivize early payment
"Pay within 10 days, deduct 2% from the invoice total."
This incentivizes customers to pay faster and saves you cash.
- Invoice: $10K
- Due: 30 days
- 2% discount if paid in 10 days: $9,800
Even though you lose $200, you get cash 20 days faster. If you need that cash for operations, it's worth it.
6. Offer multiple payment methods
Credit card, ACH transfer, wire, check. The easier you make it to pay, the faster they pay.
7. Align sales and finance
Sales team should understand DSO matters. If they give a huge discount to close a deal, but also give net 90 payment terms, they've created a cash drain.
Rule: DSO is sales' problem too. Don't ignore it.
8. Consider factoring or credit lines
If DSO is killing cash flow and customers won't pay faster, you can:
- **Factor invoices:** Sell unpaid invoices to a lender at a discount, get cash immediately
- **Credit line:** Get a business line of credit for working capital
This is expensive but sometimes necessary for growth.
Calculating Your Actual DSO
Method 1: Simple calculation
AR = $500K (current unpaid invoices)
Last 30 days revenue = $200K
DSO = ($500K / $200K) × 30 = 75 days
Method 2: More accurate (based on receivables aging)
Most of AR is current (<30 days). Good sign. If most AR is 90+ days overdue, you have a problem.
DSO Best Practices
Don't give net 60/90 unless necessary
Unless you're selling to enterprise or government, stick with net 30.
If net 30 is your policy, enforce it. If you're lenient with one customer, others will expect leniency.
Track individual customer DSO
Some customers consistently pay late. Maybe they get different terms or a price adjustment.
Incentivize early payment
2% discount for payment in 10 days adds up.
If DSO is increasing (40 days → 50 days → 60 days), you have a problem. Investigate why.
Key Takeaways
- DSO measures average days to collect payment
- Lower DSO = faster cash flow = more flexibility
- B2B benchmark is 30–45 days; aim for this range
- Make invoices clear, send immediately, follow up on overdue
- Offer early payment discount (2% for net 10 or 15)
- Align sales and finance on importance of DSO