Excuse 4: Did not agree 30 days

Applicability

Payments late on 30 day terms, but usually only makes sense on first penalty

Customer understands penalties but believes a longer credit term was agreed
In our case, terms are clearly stated on the agreement and the invoice, so a bit late to say they were not agreed now If the terms were not agreed (which is the case if customer thinks one thing and supplier thinks another) statute defines a default of 30 days anyway
Customer used standard terms on purchase order which have longer than 30 day terms
It does not necessarily mean that the terms on the purchase order are the ones that apply If they do apply, and are unreasonably long then the late payment act does have a remedy for this It may be that the supplier agrees to the customers longer term

If nothing else, the penalty has prompted a dialogue to actually agree terms - a credit of the first penalty defuses the situation, and terms can be formally agreed for future invoices.
If not the first occasion, reference can be made to previously formally agreed terms, and if the payment was late the penalties stand