Teams based in Suji-gu and across Gyeonggi-do often run bilingual invoices while their billing engine thinks in a single tax profile. The mismatch shows up as tiny rounding differences that grow annoying at portfolio scale—or as customer tickets about invoice language that finance cannot easily reproduce.
Rate switches mid-subscription
When a customer’s tax status changes, decide whether historical open invoices rewrite or whether only future cycles adopt the new rate. Document the choice. Auditors dislike silent rewrite policies more than they dislike either explicit option.
Settlement timing
Card settlements and tax reporting calendars do not always share a week boundary. Our VAT Overlay seminar walks a sample month where cash hits on a Friday and the tax pack closes on a Thursday—simple on a whiteboard, messy in a spreadsheet.
Training, not legal advice
Smartnetinfrastructure teaches operational literacy. For statutory positions, involve your tax advisor. We exist so that advisor conversation starts with clean event history rather than apologetic screenshots.