Bookkeeping for E-Commerce Sellers: What Online Store Owners Need to Know

Selling online looks simple from the outside — list a product, take orders, ship them out — but the bookkeeping underneath an e-commerce business is genuinely more complicated than a typical service business. Multiple sales channels, payment processors that take their own cut before the money ever hits your bank, inventory that needs to be tracked and costed, and sales tax obligations that can span far more places than you'd expect. Here's what online store owners need to have in place.

Multiple payment processors muddy the picture

Most online sellers aren't collecting money through just one channel. Between Shopify Payments, PayPal, Stripe, Amazon, Etsy, and marketplace-native checkout systems, a single sale might land in your bank account through any number of paths — and each processor reports things slightly differently, on its own schedule, after taking its own fees out first. If your bookkeeping just looks at "deposits hitting the bank," you'll miss the fact that a $100 sale actually landed as $96.10 after processing fees, and you'll misstate both revenue and expenses if you don't separate the two.

The fix is to record the gross sale amount as revenue and the processor's cut as a separate expense line, rather than just booking whatever number shows up in your bank feed. That distinction matters for understanding your true margins, and it matters for accurately reporting revenue if you're ever asked to substantiate your numbers.

Inventory and cost of goods sold (COGS)

If you sell physical products, inventory is one of the biggest places DIY bookkeeping goes wrong. Buying inventory isn't an expense the moment you pay for it — it's an asset sitting on your balance sheet until it actually sells, at which point its cost moves to cost of goods sold and reduces your gross profit on that sale. Businesses that expense inventory purchases immediately (because that's what hit the bank account that month) end up with a profit and loss statement that swings wildly and doesn't reflect what's actually happening in the business.

Getting COGS right requires some consistent method for tracking what inventory costs — whether that's a simple average cost, FIFO, or software that syncs with your storefront platform — and updating it as you receive new stock and as items sell. It's more work than a service business's books, but it's also where a lot of e-commerce owners discover their margins are thinner (or fatter) than they assumed.

Sales tax across regions

Selling online can trigger sales tax collection obligations in places you've never set foot in, once your sales into a given state or region cross a certain threshold ("economic nexus"). Marketplaces like Amazon and Etsy often collect and remit sales tax on your behalf for sales made through their platform — but if you also sell direct through your own storefront, you may be responsible for tracking and remitting sales tax there yourself, and the two systems don't always reconcile cleanly. Bookkeeping needs to track sales tax collected separately from revenue (it's not your money — you're just holding it for the tax authority) and flag which channels are handling remittance versus which aren't.

Reconciling marketplace fees

Beyond payment processing fees, most marketplaces charge their own layer of fees — referral fees, fulfillment fees, advertising spend, subscription fees for seller accounts — often bundled into a single periodic payout that's hard to unpack line by line. A $5,000 payout from a marketplace might represent $6,200 in gross sales minus $1,200 in various fees, and if your books just record "$5,000 deposit" as revenue, you're understating sales and overstating your true expense ratio. Good e-commerce bookkeeping pulls the settlement report apart and books gross sales, fees, and net payout as separate line items, so you can actually see what each channel is costing you.

Why this is harder than typical small business bookkeeping

Compared to a straightforward service business, e-commerce bookkeeping usually involves more transaction volume, more reconciliation points (one per payment processor and marketplace), inventory accounting, and multi-jurisdiction sales tax — all of which add up to real complexity that a basic spreadsheet or a once-a-quarter catch-up session won't handle well. It's exactly the kind of business where falling behind for even a couple of months can turn into a significant reconstruction project. If you're comparing bookkeeping vs. accounting for your online store, know that the bookkeeping side (keeping the day-to-day transaction and inventory data accurate) is where most e-commerce sellers actually struggle — see our bookkeeping vs. accounting breakdown for how the two roles divide the work.

The upside is that once your books correctly separate gross sales, processing and marketplace fees, and COGS by channel, you get a genuinely useful picture: which channel is actually most profitable, whether a given SKU is worth keeping, and whether your pricing covers your real costs — not just your guess at them.

Where to start

If your bookkeeping right now is "whatever the bank balance says," start by separating gross revenue from fees for your biggest sales channel, and get a simple inventory tracking method in place even if it's imperfect — an approximate COGS beats none at all. For a business with real transaction volume across multiple channels, outsourcing this to a bookkeeper who's comfortable reconciling payment processors and marketplace settlement reports tends to pay for itself quickly; see our take on how much a bookkeeper actually costs for how that pricing typically works.

Linked-do-Books works with online sellers on Shopify, Amazon, Etsy, and beyond — reconciling every processor and channel into one clean set of books every month, wherever you and your business are located.