Many commercial contracts specify the price but say surprisingly little about delayed payment.
A useful payment clause should consider due dates, invoicing requirements, taxes, disputed invoices, interest or other contractual consequences where lawful, suspension of services, security, termination and recovery mechanisms.
The goal is not to make the contract aggressive. It is to make the financial consequences predictable.
Businesses should also preserve proof of delivery and acceptance, purchase orders, invoices, statements of account and communications concerning outstanding amounts.
If a payment dispute later reaches court, the quality of the underlying records can become as important as the contract itself.
Credit risk is a legal issue as much as an accounting issue.