Calculate True SKU Net Profit from Amazon Settlement Reports

Amazon's Settlement Report (GET_V2_SETTLEMENT_REPORT_DATA_FLAT_FILE) is delivered as a Tab-Separated Values (TSV) file, not CSV — which causes immediate parsing failures when tools assume comma delimiters. More critically, the report uses an extremely flat transaction model where each row represents a single event type (Order, Refund, Adjustment, FBA Fee, Commission) rather than aggregating per order. A single order generates 4-6 rows: one Order row with product_sales revenue, separate rows for fba_fees, commission, and shipping_credits, and if refunded, additional rows with negative values in product_sales and positive reversals in fee columns. The accounting trap: when building a Pivot Table to calculate net profit per SKU, naive summation of the amount column double-counts refunds because the original sale and the refund reversal both appear as separate line items. Additionally, fee columns like selling_fees and fba_fees store values as negative numbers (costs), but refund rows store fee reversals as positive numbers. This workflow parses the TSV, groups transactions by amazon-order-id and sku, netting each transaction type correctly before outputting a clean per-SKU profit summary.