CPA Services for Ecommerce and Online Sellers

An ecommerce accountant handles the parts of an online business that a general preparer usually misses, because selling product across platforms and state lines creates problems a typical service business never faces. The three that matter most are inventory and cost of goods sold, multi-state sales tax nexus, and reconciling gross marketplace reporting down to real taxable income. Get any of those wrong and the return is wrong, sometimes by tens of thousands of dollars, and the error usually surfaces as a state notice or an audit rather than a polite letter. A generalist who is excellent with a dentist or a consultant can still be lost inside a Seller Central settlement report, because none of those three problems shows up in a service practice.

Start with the books, because everything else depends on them. When you sell on Amazon or Shopify, the money that hits your bank is not your revenue. It is revenue minus referral fees, minus payment processing, minus refunds, minus shipping labels, net of a dozen adjustments the platform nets out before it pays you. An ecommerce accountant records the gross sale and each of those deductions separately, so your profit and loss statement shows what you actually earned and what each platform actually cost you. A generalist who books only the deposit hides your true revenue and buries deductible fees where you never claim them, which quietly inflates the tax you pay.

Then there is inventory, which is the single biggest thing a regular accountant gets wrong for a seller. Inventory you buy is not an expense when you pay for it. It is an asset, and it only becomes a deductible cost of goods sold when the item sells. Handle this incorrectly and your profit swings wildly for no real reason, which distorts both your tax bill and your understanding of whether the business is actually healthy.

Consider a seller who did $500,000 in gross sales through Amazon and their own Shopify store. The 1099-K might report $520,000 of gross payments including sales tax collected and shipping. Actual product revenue is $500,000. Amazon fees ran $90,000, refunds were $25,000, and cost of goods sold on the units that actually sold was $200,000. A generalist booking the bank deposits might land on a garbled number. An ecommerce accountant reconstructs it properly: $500,000 revenue, minus $200,000 COGS, minus $90,000 fees, minus other operating costs, arriving at a defensible net profit that ties to both the bank and the 1099-K. That reconciliation is the core of what we do, and it flows straight out of the bookkeeping we keep every month. On top of it we carry the sales tax registrations, the income tax nexus tracking, and the year-end return, so an online seller gets one team that understands the whole machine instead of a bookkeeper, a sales tax app, and a preparer who have never spoken to each other. The IRS Small Business Tax Center sets the federal duties, and Publication 334 covers the recordkeeping, but neither tells you how to untangle a marketplace payout, which is exactly the gap we fill.

For an ecommerce seller, sales tax nexus is the rule that decides which states you have to collect and remit tax for, and the answer changed completely in 2018. Before then, a state could only require you to collect its sales tax if you had physical presence there, a store, an office, an employee, or inventory in a warehouse. Then the Supreme Court decided South Dakota v. Wayfair and upheld economic nexus, which lets a state require collection based purely on how much you sell into it, with no physical footprint required at all. That single ruling is why a seller in one state can suddenly owe sales tax duties in dozens, and why this is now the first thing we check for a new online seller.

Most states adopted a threshold modeled on the one the Court approved: $100,000 in sales into the state, or 200 separate transactions into the state, measured over the current or prior year. Cross either trigger and you are expected to register with that state, collect the correct tax on taxable sales going forward, and file returns on whatever schedule the state assigns. The specifics vary in ways that matter. Some states use only the dollar figure, several have dropped the 200-transaction count because it swept in tiny sellers, and the sales that count toward the threshold differ from state to state. There is no single national rule, which is exactly why this is hard to self-manage as you grow into new markets.

Marketplace facilitator laws are the piece that keeps this from being catastrophic. Nearly every state now requires the marketplace itself, Amazon, Etsy, Walmart, eBay, to collect and remit sales tax on the sales it processes, so for your Amazon and Etsy orders the platform is handling the tax, and in many cases those facilitated sales still count toward your economic nexus threshold even though you are not the one remitting. The exposure lives in the sales the marketplaces do not cover, chiefly your own Shopify store, your BigCommerce site, or anything you sell direct where you are the merchant of record.

Here is how it plays out. Say your Shopify store ships $130,000 of product into Texas this year across 900 orders. You have blown past the $100,000 economic nexus threshold, so you are required to register with the Texas Comptroller, collect Texas sales tax on taxable orders shipped there, and file returns. If you do not notice until eighteen months later, you owe the uncollected tax out of your own pocket plus penalties and interest, because the obligation existed whether or not you charged it to customers. On a $130,000 sales base with roughly 8% combined tax, that is over $10,000 of tax you may have to eat, plus penalties on top. We prevent that by tracking your sales by state through tax compliance and registering you the moment a state actually requires it. The multi-state framework is documented by the Streamlined Sales Tax governing board, and the decision itself is in the Wayfair opinion.

For an ecommerce seller, inventory and cost of goods sold are the heart of the tax picture, and mishandling them is the most common and most expensive mistake we see. The core rule is that buying inventory is not a deductible expense. When you spend $40,000 restocking product, you have not lost $40,000, you have converted cash into an asset that sits in a warehouse. That purchase only becomes a deduction, as cost of goods sold, when the specific units actually sell. Until then it stays on your balance sheet as inventory, and no amount of cash leaving your account changes that.

Sellers who ignore this and expense every purchase when the money leaves their account produce financial statements that are pure fiction. In a heavy buying quarter they show a loss they did not really have, then in the following period they show inflated profit because the sold goods carry no recorded cost. The tax consequence is a rollercoaster: a low bill in a stocking year followed by a brutal one later, all because the timing of deductions was tied to cash instead of to sales. The cost of goods sold method fixes this by matching the cost of each item to the period it sells in, so your gross margin is honest and your taxable income reflects reality rather than the rhythm of your purchase orders.

The mechanics run through a simple formula. Beginning inventory, plus purchases during the year, minus ending inventory, equals cost of goods sold. That means you need an accurate count and value of what is left on the shelf at year end, because ending inventory directly reduces your deduction. If you carry $60,000 of unsold product on December 31, that $60,000 is not deductible this year no matter how much cash you spent. Your valuation method matters too. First-in first-out assumes the oldest units sell first, while a weighted average smooths cost across all units, and in a period of rising supplier prices the method you pick changes both your COGS and your ending inventory value, which is why we pick it deliberately rather than by accident.

Here is a worked example. You start the year with $50,000 of inventory, buy $200,000 more during the year, and finish with $60,000 still on hand. Your cost of goods sold is $50,000 plus $200,000 minus $60,000, which equals $190,000. If your sales were $400,000, your gross profit is $210,000 before operating expenses, a clean and defensible figure. Compare that to the seller who simply deducted the full $200,000 of purchases and ignored the $60,000 still in the warehouse, overstating the deduction by $60,000 and understating taxable income by the same, which is exactly the kind of error a state or the IRS unwinds on audit. Landed cost adds another layer for importers, because customs duties, freight, and inbound shipping belong in the inventory value, not in a separate expense bucket. We build the whole COGS schedule as part of your monthly financial reporting so the number is right all year, not reconstructed in April. The federal standards for inventory and accounting methods are in IRS Publication 538 and Publication 334.

The Form 1099-K is the information return that payment processors and online marketplaces file with the IRS to report the gross payments they ran through for you, and for an ecommerce seller it is a frequent source of panic and mismatched returns. For 2026 the reporting threshold reverted to its long-standing level: a platform must issue you a 1099-K once you exceed $20,000 in gross payments and more than 200 transactions in the year. Earlier plans to drop that threshold to a much lower figure were reversed, so many smaller sellers will not receive the form at all, though that changes nothing about the duty to report income you actually earned.

That last point is where sellers get into trouble, so it bears stating plainly: the 1099-K threshold governs whether a form gets mailed, not whether the income is taxable. Every dollar your store earns is reportable whether or not a 1099-K arrives. If you do $18,000 in sales and receive no form, that $18,000 still belongs on your return. The threshold is an information-reporting trigger for the platform, not a floor below which income is tax-free, and treating it as the latter is how sellers end up with underreported income and an unpleasant letter a year or two down the road.

The reconciliation problem is the bigger one. A 1099-K reports gross payments, the total buyers paid before anything was netted out. That gross number includes the marketplace referral fees the platform kept, the payment processing fees, sales tax that was collected, shipping charges you collected and then paid to carriers, and it is stated before any refunds you issued. If you report only what landed in your bank account, your revenue will be far lower than the gross figure the IRS was handed, and that gap is a classic audit flag. The fix is not to report the inflated gross either, because you never kept it. The fix is to report true gross revenue and then separately deduct every fee, refund, and pass-through so the return reconciles cleanly to both the 1099-K and your bank statements.

Here is the math on a real case. Your Amazon 1099-K shows $250,000 of gross payments. Of that, $45,000 was Amazon referral and fulfillment fees, $15,000 was refunds to customers, and $12,000 was sales tax Amazon collected and remitted on your behalf. Your true product revenue is around $223,000 after backing out the sales tax that was never yours, and the $45,000 in fees and $15,000 in refunds are legitimate reductions that a careless return would miss entirely. Reported correctly, you are taxed on real profit, not on the $250,000 headline, and the difference in tax on that gap can run into five figures. We perform this reconciliation on every ecommerce return and tie it to the bookkeeping so the numbers already agree before filing, which also means that if the IRS ever questions the gap between your 1099-K and your reported revenue, the answer is already documented line by line rather than reconstructed under pressure. The IRS walks through the form on its Understanding Your Form 1099-K page, and the underlying income rules are in Publication 334.

Two structural questions come up for a growing ecommerce seller, and both are about not overpaying as the business scales: whether to elect S-corporation status, and where you owe state income tax. They are separate issues, but a seller crossing into real profit usually hits them at the same time, so we handle them together rather than one at a time a year apart.

Take the entity question first. Most sellers start as a sole proprietor reporting on Schedule C, or a single-member LLC taxed the same way. In that setup, the entire net profit of the store is subject to 15.3% self-employment tax on top of income tax. Electing S-corporation status changes that math. As an S corporation, you pay yourself a reasonable salary that carries payroll tax, and the remaining profit passes through to you as a distribution that avoids self-employment and payroll tax. The tradeoff is added cost and formality: you have to run real payroll, file a separate 1120-S return, and defend the salary as reasonable under IRS rules. Below roughly $50,000 of profit the savings rarely cover that overhead, and above about $80,000 they often do.

Here is a worked example. Suppose your store nets $120,000 and a reasonable salary for the work you do is $70,000. As a sole proprietor, close to the full $120,000 faces self-employment tax, roughly $16,000 after the base adjustment. As an S corporation, only the $70,000 salary carries payroll tax, about $10,700, while the $50,000 distribution escapes it. That is a saving near $5,000 a year before subtracting maybe $1,500 to $2,500 of added payroll and filing cost, so you come out several thousand ahead, every year, for a structure we set up once through entity formation and structuring. Many sellers also claim the 20% qualified business income deduction under Section 199A, which stacks on top for eligible pass-through income and sweetens the case further.

Income tax nexus is the second question, and it is easy to forget because sales tax gets all the attention. A number of states now assert that enough economic activity creates an income tax or gross receipts filing duty for a remote seller, not just a sales tax one. So a profitable online store can owe income tax returns in several states, each apportioning a slice of your profit based on the sales delivered there. This is separate from the Wayfair sales tax thresholds and follows its own state-by-state rules. A seller shipping heavily into a handful of states can find themselves filing four or five state income tax returns, and missing them creates back liabilities that compound with interest. We map where you genuinely have an income tax filing duty, keep the return count from ballooning past what the law actually requires, and coordinate it with the federal return and the broader small business tax planning so the whole structure is handled as one picture. The S-corporation rules are on the IRS S corporations page, and the reasonable-compensation standard is covered in the IRS Small Business Tax Center.