Late Payment Cash Flow Calculator
See exactly how much money is trapped in outstanding invoices and what late payments cost your business per year. Enter your revenue, terms, and how late clients typically pay — get your real cash flow impact instantly. Free, no account needed.
What the Numbers Mean
Total money tied up in unpaid invoices. Calculated as (daily revenue) × (average days outstanding). This is cash you have earned but cannot use.
The monthly financing or opportunity cost of having that AR float unavailable. Based on your borrowing rate ÷ 12.
Total annual cost of late payments. What you pay in interest (or forgo in investment returns) because of money tied up in AR.
The Hidden Cost of Late Payments
The direct cost (interest on AR float) is only part of the story. Late payments also cost:
- Time spent chasing: The average small business spends 1.5 hours per week chasing late payments — roughly $3,900/year at a $50/hour rate.
- Stress and relationship strain: Chasing clients damages relationships. Late payments force difficult conversations that cost you future work from those clients.
- Missed opportunities: Cash tied up in AR cannot be deployed into growth, inventory, equipment, or staff. The opportunity cost compounds over time.
- Bad debt write-offs: The longer an invoice goes unpaid, the lower the probability of collection. Invoices over 90 days overdue have a 30%+ write-off rate in most industries.
Frequently Asked Questions
How do late payments affect cash flow?+
Every day a client takes to pay beyond your agreed terms is a day that money is unavailable to you. If you invoice $15,000 per month on Net 30 terms and clients pay 21 days late on average, you have roughly $25,500 permanently tied up in outstanding invoices. At an 8% borrowing rate, that costs about $2,040 per year in interest — plus the stress and time spent chasing. The calculator shows you your exact number.
What is accounts receivable float?+
AR float is the total amount of money tied up in unpaid invoices at any given time. It equals: (daily revenue) × (average days outstanding). If your average invoice takes 45 days to collect and you invoice $500/day, your AR float is $22,500 — money that has been earned but not yet received. Reducing your average collection time reduces your float and improves working capital.
What is a good borrowing/opportunity rate to use?+
Use your actual borrowing rate if you have a credit line or overdraft (typically 6–12% in 2026). If you have no debt, use your expected investment return or savings rate. If you are uncertain, 8% is a reasonable middle ground. The rate determines the annual cost of having money tied up in AR rather than available to you.
How do I reduce cash flow impact from late invoices?+
Five proven approaches: (1) shorten payment terms — Net 14 vs Net 30 frees 16 days of daily revenue; (2) invoice on delivery, not monthly; (3) chase immediately on day 1–2 overdue — early contact resolves 60–70% of late invoices; (4) require deposits for new clients; (5) implement automated reminder sequences. Each reduces your average days outstanding and shrinks your AR float.
What payment terms reduce cash flow risk the most?+
Shorter terms reduce both your float and your exposure to payment problems. Ranked best to worst for cash flow: Due on Receipt > Net 7 > Net 14 > Net 30 > Net 45 > Net 60 > Net 90. Most clients accept Net 14 without pushback. For new clients or high-value projects, requiring a 25–50% deposit further reduces your risk — you are only floating the remaining 50–75%.
How does invoice tracking help cash flow?+
Consistent, timely follow-up is the single most effective tool for reducing late payment — and therefore improving cash flow. A business that chases on day 1–2 overdue collects 30–50% faster than one that waits 2–3 weeks to follow up. Invoice tracking software ensures every overdue invoice gets chased at the right time, without relying on memory or manual processes.
The Real Cost of Late Invoices — and How to Reduce It
Most small businesses think of late invoices as an inconvenience. The calculator above makes the actual cost concrete. For a business invoicing £15,000/month on Net 30 terms with clients paying 21 days late, the AR float is over £25,000 — money that has been earned but is sitting in someone else's account. Understanding cash flow mechanics helps quantify this: at an 8% opportunity cost, that is £2,000+ per year. And this is before accounting for the time spent chasing.
The Payment Terms Lever: Fastest Way to Reduce Float
The single fastest way to reduce your AR float is to shorten your payment terms. Net 30 to Net 14 reduces your average collection window by 16 days. For a business with £20,000 monthly revenue, that frees approximately £10,600 in working capital — immediately, from day one, without any change to your follow-up process. Most clients accept Net 14 without negotiation. If a client insists on longer terms, factor the extended period into your rate — you are providing credit, and credit has a cost. For a full guide on setting and negotiating terms, see the payment terms guide.
The Follow-Up Lever: Reducing Average Days Late
Even with good payment terms, clients pay late. The follow-up speed is what determines how late they pay. Research consistently shows that businesses that follow up on day 1–2 overdue collect 30–50% faster than those that wait 7–14 days to send the first reminder. The mechanism: early contact catches administrative oversights before they become deliberate deferrals. A client who missed the due date because of an approval queue is easily resolved with a quick email. The same invoice at 30 days becomes a negotiation.
Use the invoice follow-up schedule planner to set exact chase dates from your invoice due date, and the payment reminder email generator to draft the right email for each stage.
Deposits: Eliminating Float Before It Starts
For project-based work, requiring a 25–50% deposit upfront eliminates half your collection exposure before the work begins. If you take a 50% deposit on a £10,000 project, you only need to collect £5,000 after delivery — halving both your AR float and your bad debt risk. For new clients, a 50% deposit is standard and professionally appropriate. For ongoing retainer clients with a good payment history, a smaller deposit (25%) or no deposit is reasonable.
The full guide on preventing late payments is at how to avoid late payments. For the broader picture of how businesses handle overdue invoices, see late payment statistics 2026.
You've calculated what's trapped. Now free it.
Every day an invoice goes unchased is another day of your money sitting in someone else's account. InvoiceGrid shows you exactly which invoices to chase today — consistently cutting weeks off average collection time.
- ✓See which invoices are costing you the most cash flow right now
- ✓Systematic chase process that gets invoices paid faster without damaging client relationships
- ✓Late payment history per client — so you can price the risk before you take on new work
Also useful: DSO calculator · Late fee calculator · Follow-up schedule planner · How to avoid late payments · How to handle late payments