One of my international clients didn't pay an outstanding invoice for about 5 months (on 28 day terms).
After several reminders by email, I eventually reissued the original invoice to include a late payment charge (which is mentioned in my invoice terms). I calculated the charge using a govt calculator online.
The client eventually paid the original invoice amount but didn't pay the late payment charge. I'm not too concerned about pursuing them for the extra fee (esp as they are not in the UK) but how do I reflect this in my accounting, as the reissued invoice has effectively gone unpaid?