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The Best Way to Merge Shopify and Mercari Data for Handoff to Your Accountant
If you're doing handoff to your accountant by hand right now, here's the fastest path from "two exports" to "one usable sheet," and why the manual version keeps breaking.
Step by step
- Decide your target columns once. Most people settle on Date, Channel, Order ID, and Total — set that up in CSV Experts and you won't redo it.
- Import the Shopify file first. The first time you see this file shape, you map each of its columns to your target list.
- Import the Mercari file the same way. Its columns get mapped once too — after that, every future file with this shape merges with no extra clicks.
- Check the merged totals. Dates and numbers are normalized automatically, so a European "24,00" and a US "24.00" both land as the same value.
- Export. CSV or Excel, ready for handoff to your accountant.
What actually goes wrong if you do this by hand
Shopify gives you a Created At timestamp that includes a timezone offset, while Mercari gives you a sold date in the seller's local time — line those up manually across a few hundred rows and it's easy to miscount a week. On top of that, Shopify's export exports one row per line item by default, so an order with 3 products becomes 3 rows unless you export the summary report instead, and Mercari's like other reseller apps, the export is minimal with no tax breakdown and mixes cancelled orders into the same file. Individually those are minor quirks; combined into one spreadsheet by hand, they're where most reconciliation errors for handoff to your accountant actually come from.
Why it matters for handoff to your accountant
Handing raw multi-platform exports to an accountant usually means paying them to do the cleanup you could do yourself in a few minutes.
Just want the quick column-difference reference instead? See the short version.