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Merge Amazon Seller Central and Wayfair Sales Data for Tax Prep

At tax time you need total revenue by channel without hand-fixing each export's columns first.

Why Amazon Seller Central and Wayfair exports don't line up

Amazon Seller Central: a purchase date/time column stamped in UTC, not your local time; item price, promotion discounts, and Amazon referral fees split across several columns; an Amazon Order ID in a long dashed format (e.g. 123-4567890-1234567). Also, reports differ noticeably between the 'All Orders' report and the Payments/Settlement report — totals rarely match at a glance.
Wayfair: a purchase order date distinct from the ship date required by Wayfair's supplier terms; wholesale cost, freight allowance, and Wayfair's referral fee as separate columns; a Purchase Order (PO) number rather than a typical order ID. Also, built for suppliers rather than direct-to-consumer sellers, so column names lean toward logistics (PO, ship window) rather than retail checkout fields.

For tax prep, that mismatch is exactly what causes hours of manual cleanup every period.

Open CSV Experts and set your target columns once (Date, Channel, Order ID, Total).
Drop in your Amazon Seller Central export and map its columns once.
Drop in your Wayfair export and map it the same way — both merge into one sheet, normalized.
Export as CSV or Excel. Same-layout files merge automatically next time.

No. Everything runs in your browser using JavaScript — your files are never sent to a server.

Yes. Add as many source files as you want; each distinct file layout is mapped once and remembered.