Ok, Lord knows why I am aware of this stuff, it's not my job, but these days there are pretty strict rules about invoice payment for companies registered in the UK over a certain size. Partly to protect small suppliers and partly because slow payment of invoices can be seen as an attempt to massage profit/loss figures for a particular reporting period, which I believe (IANAA or L) is a very dodgy practice, possibly illegal. So, invoice payment needs to be reported on every reporting period and will also be part of any financial audit.
Unilever, to take one example, is an international company, but appears to trade in the UK with a UK Ltd subsidiary company. Unilever UK Ltd. It's accounts are filed at Companies House and I've only skim read them, but pretty certain they are trading at a level that would make them eligible under the reporting rules:
https://find-and-update.company-information.service.gov.uk/company/00334527/filing-history - report here for the forensically minded among you.
The rules for reporting and payment are here:
They are complicated, but essentially it's very unlikely that Unilever have standard payment terms longer than 90 days and they will be paying undisputed invoices within that time period. I would hazard a guess that it's more like 60 days these days, for various accounting reasons, and that most invoices are paid with alacrity because averages of payment times are taken under the reporting rules, so the more you pay quickly, the more time you get over disputed invoices or tricky cases.
I would imagine, for a smallish (to them) invoice of £10k (to pick a random sum of money), would be paid quickly and without fuss. However, it's worth noting that the countdown only starts
once an invoice has been submitted formally, so if there's a considerable delay in payment it's reasonable to assume that one cause could be that the supplier failed to submit an invoice for work done in a timely fashion.
Thus concludes both the most boring post of the day and your early(ish) morning accountancy briefing. Provided by NO SORT OF ACCOUNTANT AT ALL. I am just accountant-adjacent.
TL,DR - There are rules that big companies have to adhere too. Casual late payment of invoices just doesn't happen anymore. Once more, I am not an accountant.