Your unpaid invoice is not losing value. It is losing recoverability.
At 30 days overdue, a commercial debt has roughly a 90% recovery probability. At six months, 67%. At twelve months, below 50%. These are not projections. They are what happens when debtors use time as a strategy and creditors use politeness as one.
The question is never whether collection costs too much. It is what the alternative costs.
The three fee models
Contingency: you pay nothing upfront and nothing if we don't collect. The fee is a percentage of the recovered amount — typically 5% to 25%, depending on the debt's age, size, jurisdiction, and how creatively the debtor has been avoiding you. This is the model most B2B creditors use and the one that aligns incentives in the same direction.
Flat fee: a fixed amount per case, usually €200 to €1,500, regardless of outcome. Works for high-volume, low-value portfolios where the arithmetic runs at scale.
Hybrid: a small upfront fee plus a reduced contingency. Used when investigation comes before collection — tracing assets, confirming the debtor entity still exists, establishing which jurisdiction's courts have the leverage.
Most international B2B debts over €10,000 go contingency. No win, no fee. The agency carries the risk.
The number nobody calculates
A €100,000 write-off is not €100,000 of lost revenue.
If your net margin is 10%, you need €1,000,000 in new sales to replace what you wrote off. A million euros of new business — sold, delivered, and collected — to get back to where you stood before one client stopped paying.
Against that arithmetic, a 15% collection fee on a successful recovery is not an expense. It is the highest-returning use of your finance department's afternoon.
What moves the percentage
Four variables: age, size, jurisdiction, complexity.
Age is the biggest. A 60-day-old debt from a solvent German company costs less to collect than a 14-month-old debt from a shell entity in a jurisdiction where courts close for three months in summer. The first is a phone call and a legal letter. The second is an operation.
Size works in your favour. Larger debts attract lower percentages because the absolute fee is adequate at a smaller rate. A 7% fee on €500,000 is more than a 20% fee on €15,000.
Jurisdiction determines the legal infrastructure. Germany's Mahnverfahren — an automated payment order, €36 filing fee for a €10,000 claim — is fast and cheap. Brazil's judicial system is not. The collection route follows the debtor's legal landscape, not your preference.
Complexity is everything else. Disputed invoices, insolvency, successor liability when the company has been sold, assets distributed across borders. Each layer adds work. The fee reflects the work, or it reflects a promise that cannot be kept.
When writing off is the right decision
Sometimes the debt is not worth pursuing. The debtor has no assets. The jurisdiction has no enforcement mechanism your commercial case can access. The amount is below the economic threshold where recovery exceeds its own cost.
A professional agency tells you this in the first assessment, before engagement, because chasing an uncollectable debt is a second loss on top of the first. Your fourth polite email was not a strategy. Neither is hiring someone to send a fifth.
The honest answer to "how much does it cost" is: less than you think if the debt is real, and nothing if it isn't — because a credible agency will not take a case it cannot win.
Free case assessment. 48-hour written response. If the debt isn't worth pursuing, we'll say so.