Invoicing runs late
The work finishes, the next project starts, and the invoice gets raised whenever someone remembers. Paid late follows automatically.
Your time is the product. Every hour spent reconciling a bank feed is an hour not billed, and it is almost always worth less than the hour you gave up to do it.
Service businesses usually have clean, low-volume books. The problems are not about volume — they are about invoices going out late and nobody chasing them.
The work finishes, the next project starts, and the invoice gets raised whenever someone remembers. Paid late follows automatically.
Chasing a client you want to keep working with feels awkward, so it does not happen. The balance quietly grows.
Drawings, personal subscriptions and business spending on the same card, especially in single-director companies.
Software billed monthly in small amounts, in several currencies, that nobody has reviewed since it was signed up for.
Work subcontracted out, with the employee-versus-contractor question and the paperwork that goes with it.
A few large invoices rather than many small ones, so one late payment is a genuine cash flow event.