How do I track inventory and sales across Amazon, Shopify, and eBay in one set of books?

The biggest mistake multichannel sellers make is recording Amazon, Shopify, and eBay deposits as single income transactions from their bank feed. That deposit from Amazon isn’t your revenue. It’s a net payout after Amazon has already deducted marketplace fees, refunds, advertising costs, and FBA charges. If you record the deposit as income, your books understate actual revenue and completely hide what it costs to sell on each platform.

The right approach is using a multichannel integration tool like A2X, Bookkeep, or Klayena. These tools connect to each sales platform and to QuickBooks Online, then summarize each platform’s daily or settlement-period activity into detailed journal entries. Instead of one mystery deposit, you get a clean breakdown of gross sales, marketplace fees, shipping costs, refunds, and the net payout. That level of detail is what makes your financial reports actually useful.

Your chart of accounts setup matters just as much as the tool itself. Each sales channel should have its own income account or class in QuickBooks Online. You want to pull a profit and loss report filtered by Amazon, Shopify, or eBay individually. Without that separation, you might see that your total business is profitable while having no idea that one platform is actually losing money after fees and returns. Channel-level profitability is the whole reason for doing this correctly.

For inventory, the challenge is that your stock is often shared across platforms but sold through different channels at different price points with different fee structures. Your integration tool handles the sales and fees side, but you still need accurate cost of goods sold. That means maintaining proper inventory records with consistent unit costs. If you’re using FBA for Amazon but self-fulfilling Shopify orders, your fulfillment costs differ by channel and your books should reflect that difference.

Reconciliation ties everything together. Each platform settles on its own schedule. Amazon might pay every two weeks, Shopify daily, and eBay weekly. The integration tool creates journal entries when sales happen, and then you match the actual bank deposit to the expected payout. When the numbers don’t match, you catch discrepancies quickly instead of discovering a $3,000 problem six months later.

Sales tax adds another layer. Amazon handles collection and remittance in most states through Marketplace Facilitator rules, but Shopify may require you to manage it depending on your configuration. Your books need to track what was collected and by whom so you don’t double-report or miss a filing in Florida or any other state where you have nexus.

If you’re already selling on multiple platforms but your books are a mess of lump-sum deposits with no detail, that’s fixable. Our bilingual bookkeeping services include getting your integration tools connected and your QuickBooks Online chart of accounts structured properly. The upfront setup takes some effort, but it saves hours every month and gives you numbers you can actually trust.

The sellers who scale successfully on multiple platforms are the ones who know their real margins by channel. Guessing which platform performs best based on gross sales alone leads to bad decisions. With the right tools and proper accounting structure, your books tell you exactly where to invest more and where to cut back. That kind of clarity is what turns an e-commerce business from a side hustle into something that grows intentionally.