eBay Transaction Report CSV Validator

A client's eBay transaction report had fee columns showing positive values instead of negative — someone had opened it in Excel and run a find-and-replace that stripped the minus signs. QuickBooks imported every fee as income instead of an expense. Their P&L was off by $6,400 before we caught it. The validator flags any fee that isn't negative, so I would have seen it in seconds.

I downloaded three months of eBay transaction reports to do quarterly taxes and didn't realize the exports overlapped by two weeks. Had 340 duplicate transactions that inflated my gross by $9,200. The IRS would have had questions. Now I run every export through the validator first — the duplicate detection catches overlapping date ranges immediately.

eBay's managed payments export had rows where the Transaction creation date was completely blank — about 15 rows scattered through a 2,000-row file. My accounting software assigned them to January 1, 1970, which threw off every monthly report. The row-level validation catches empty required fields and gives me exact row numbers so I can fix them in the source before importing.

My eBay export had dates in DD-MMM-YYYY format but my QuickBooks was set to MM/DD/YYYY. The import didn't fail — it silently swapped days and months wherever the day was 12 or under. February transactions ended up in December, March in November. I only found it when VAT filing didn't match. The validator catches date format mismatches across regional settings before they silently corrupt your books.