Well, cash flow has been a tad off this month, and finally I have tracked it down. Things like this niggle at me, as you can imagine.
Thanks to the customer that raised this - actually telling me that we gave him extra credit. He did not have to, but it was useful understanding what happened.
The problem is the Queen's Jubilee! Or more specifically the extra bank holiday right at the start of the month.
We have a number of customers who are billed on 1st of each month but selected Direct Debit on the 9th. Well, obviously "the 9th" has some leeway as it could be a weekend, etc, but within a couple of days on or after the 9th is how it normally works. We allow people to pick one of four dates during the month for collection of Direct Debits.
The problem is that people billed on 1st June could not get the agreed notice for Direct Debits (we work on 5 working days notice) before the 9th, or 10th, or 11th. Normally this does not happen, but the extra bank holiday pushed it too far, and the cautious programming in the accounts system erred on the side of the customer and gave all those affected an extra month's credit. So hundreds of people billed on 1st June are paying on 9th July rather than around 12th June.
The system did what it was told, it was not actually an error (which is why we had trouble finding it), but I have changed the rules for the future. It now allows 3 working days after the "agreed" day in the month. By allowing working days it should cope with things like this (which could happen for an Easter). The DD rules allow 3 working days after notified collection date so this is consistent with the rules, even though it would mean notifying a later date in our case.
The invoices we sent were, of course, right, and clearly stated the extra (interest free) credit terms. The DD notices are, of course, right. The payments are not seen as "late" and no penalties charged. The system did what it was told!
What worries me with this is not just the tens of thousands of pounds of payments delayed by a month, but the fact I can pretty much guarantee that someone will complain! Someone will be unhappy paying two months in July even though they paid nothing in June, and even though the typical amount is around £20. I will be really pleased to be proved wrong on this. I am sure 99% of affected customers will not complain, and many will realise that we have given them a month's free credit, but someone will complain I bet you...
Am I just getting cynical in my old age I wonder?
At least we have made changes to avoid this confusion in future. It is one thing making any sort of mistake, but another not to learn from it.