Late Payment Penalties in the UK

Late Payment of Commercial Debts

Applicability

All, although this generally only makes sense for the first penalty

Customer genuinely believes he has to have agreed to penalties for them to apply
Penalties are a statutory part of all commercial contracts, so he has agreed to them In our case, penalties are stated in the published T&Cs, so he has agreed to them
Customer used a standard purchase order which stated their terms and they do not include penalties
That does not necessarily mean that those terms were the ones one which the goods/services were provided However, as penalties are a statutory part of all commercial contracts, even if the customers terms were the ones agreed, those terms implicitly include penalty charges.
Customer would never enter in to a contract if they knew penalties applied
Penalties are a statutory part of all commercial contracts, so he has no choice if he wants to do business with anyone at all in the EU!

A policy of crediting the first charge works well in this case. Advise the customer of the facts of life, and credit the first penalty. Customer is now educated, but has not been penalised on this occasion. This is also a good opportunity to discuss and agree credit terms that apply as the fact that they paid late may mean they may need different credit terms or not understand the ones they have agreed.
If it is not the first penalty, then this was resolved last time and these excuses are not really valid now, so can be dismissed - customer has to pay.