Across European B2B companies, a striking pattern emerges: 60% of significant bad debt losses come from the top 10 clients. Not the small accounts you worry about. Not the new customers you scrutinize. The big ones. The trusted ones.

The average mid-market company has 23% of revenue concentrated in their largest client. Some go higher—35%, even 50%. When that client stumbles, the supplier doesn't just lose a customer. They face an existential crisis.

Trust replaces process. When a €5,000 client pays late, you send reminders on schedule. When a €500,000 client pays late, you call your contact and accept whatever explanation they give. The relationship feels too important to "damage" with strict procedures.

Terms creep outward. Big clients negotiate. Net 30 becomes net 45. Net 45 becomes net 60. "Just this quarter" becomes permanent. Before you notice, you're financing their operations with your cash flow.

Warning signs get rationalized. A small client's excuses trigger alarm bells. A large client's excuses trigger understanding. "They're restructuring." "It's a temporary cash flow issue." "They've always paid eventually." By the time you stop rationalizing, the exposure is enormous.

You're last in line. When a large company faces genuine distress, they triage their payables. Critical suppliers—the ones they need next week—get paid. Historical suppliers—the ones who delivered months ago—wait. Your five-year relationship means nothing when they're choosing between keeping the lights on and paying your invoice.

Large client defaults rarely surprise those paying attention. The warning signs follow a predictable sequence:

Stage 1: Payment velocity slows. They've always paid within terms. Now they're 5-10 days late. Nothing dramatic. Easy to overlook.

Stage 2: Communication changes. Your usual contact becomes harder to reach. Emails take longer to get responses. Calls go to voicemail more often.

Stage 3: Partial payments appear. Instead of paying invoices in full, they start "making progress" with partial payments. They're managing you.

Stage 4: Disputes emerge. Suddenly, there are quality concerns or delivery questions about invoices that were fine for months. They're creating negotiating leverage.

Stage 5: Silence. Contact stops. You're now calling their general line. The relationship that felt so solid has evaporated.

Set concentration limits. No single client should exceed 15% of revenue. If they do, treat that account with heightened scrutiny, not reduced oversight.

Monitor payment behavior, not just amounts. Track days-to-pay trends monthly. A client consistently paying 5 days slower than last quarter is sending a signal—even if they're still within terms.

Hold the line on terms. Large clients negotiate hard because it works. Every extra day of payment terms is a day you're financing their business. Know your limits and stick to them.

Escalate early. When a large client shows the first warning sign, escalate internally. Don't wait for the pattern to complete. Early intervention preserves relationships and recoveries.

Credit insure major exposures. For clients representing significant concentration risk, credit insurance transfers the catastrophic scenario to someone else's balance sheet. The premium is worth the sleep.

Consider this scenario: Your largest client represents 25% of revenue—€2M annually. They're currently 45 days past due on €350,000 in invoices. Your margin on their business is 15%.

If they default:

• You lose €350,000 in receivables
• You need €2.3M in new revenue to replace that margin (€350K ÷ 15%)
• Your cash flow gap requires bridge financing
• Your covenant ratios may breach

Now consider the alternative: at the first sign of payment stress, you engage professional collection support. Recovery rate at 45 days: 74%. At 120 days: 52%. At 180 days: 23%.

Early action on a €350,000 exposure: recover ~€260,000. Late action: recover ~€80,000.

The math is brutal but simple.

Big clients deserve respect. They've earned trust through years of business. But respect means professional boundaries, not suspended judgment.

The companies that survive client concentration risk are the ones who treat their largest accounts with more scrutiny, not less. Who monitor payment behavior more closely, not more casually. Who escalate faster, not slower.

Your biggest client might never default. But if they do, you want to have treated them like any other credit risk—not like a relationship too important to question.

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Collecty helps B2B companies manage accounts receivable risk across client portfolios—especially the large exposures that matter most. Contact us to discuss your concentration risk.