An overdue invoice is one past its due date and still unpaid.
Count, value, and age
Three readings of the same list, answering different questions.
Count tells you how many conversations you owe somebody.
Value tells you how much cash is late.
Age tells you how likely it is to arrive at all, and it is the one most worth watching. Collection probability falls steadily with time, and the drop is sharpest in the first three months.
An invoice at 90 days is a materially different asset from one at 20 days, even at the same amount. See collectible receivables.
Why it happens more than it should
Most overdue invoices in a small service business are not disputes and not refusals to pay. They are invoices that were never chased, because chasing is uncomfortable and there is always work to do instead.
The businesses that get paid quickly are rarely the ones with better customers. They are the ones that ask sooner and more consistently.
The practical rule
A short, unemotional message at seven days past due recovers a large share of what would otherwise become a 60-day problem. It works because most late payments are administrative rather than deliberate — an invoice in the wrong pile, an approval nobody chased, a payment run that missed it.
By the time an invoice is 60 days late, the same message does far less work.
Chasing them without having to decide to
Reminders can go out on a schedule rather than when somebody works up to it, which is most of why they work. See invoicing setup.
Where to see them
Money owed, aged so overdue is separated from not yet due.