An invoice paid weeks after it falls due is an inconvenience for a large company and a serious problem for a small one. The asymmetry is financial rather than administrative.
The supplier is lending without being paid for it
Work is done, materials are bought and wages are paid before an invoice is issued. Everything between that outlay and the payment is financed by the supplier.
A large customer with cash reserves treats delay as a minor timing question. A small supplier covers it with an overdraft or by delaying its own payments down the chain.
The cost is therefore real and measurable, appearing as interest and as time spent chasing rather than as a visible loss in the accounts.
Terms are set by whoever has the alternative
Payment terms are negotiated, but a supplier dependent on one large customer has little room to insist. Extended terms are frequently presented as a condition of the relationship.
Even where a term is agreed, paying late is a decision the customer makes with limited consequence. Enforcement means a dispute with the party providing most of the supplier's income.
This is why late payment persists despite widespread agreement that it is damaging. The party best placed to complain is the party least able to afford the complaint.
Rules exist but rely on the supplier acting
Legislation in many jurisdictions sets default payment periods and grants an automatic right to interest and recovery costs once a payment is overdue.
The entitlement is rarely claimed, because invoking it signals a willingness to escalate. Suppliers frequently calculate that the interest is worth less than the relationship.
Reporting requirements that oblige large firms to publish their payment performance work differently, applying reputational pressure without requiring any individual supplier to act.
Process delays are often the real cause
Much late payment is not deliberate. An invoice quoting the wrong purchase order, arriving at the wrong address or lacking an approval sits unprocessed until someone notices.
Approval chains in large organisations involve several people, any of whom may be absent, and payment runs happen on fixed dates rather than continuously.
Suppliers who understand the specific process, invoice correctly and submit before the cut-off are paid materially faster than those who do not, without any change in terms.
Financing the gap has a price
Invoice finance and factoring convert an unpaid invoice into immediate cash for a fee, which makes cash flow predictable at a direct cost to margin.
Supply chain finance arrangements offered by large buyers work similarly, letting suppliers draw early against the buyer's credit standing at a lower rate.
Both solve the symptom rather than the cause, and both mean the supplier pays for the delay. The difference is only whether that cost is visible on the invoice.