Tax Planning for E-Commerce and Amazon FBA Sellers: Inventory, Nexus, and Multi-State Sales Tax

By Yarik Yarosh, CPA ·September 5, 2026 ·Updated October 4, 2026 ·6 min read

Written by Yarik Yarosh, CPA (US & Canada) September 5, 2026 · FL CPA license AC61704 · CPA Ontario

Selling online creates tax complexity that scales with success. A small Etsy seller with $50,000 in revenue has a straightforward Schedule C filing, but an Amazon FBA seller with $500,000 in revenue has inventory in warehouses across 20+ states, economic nexus for sales tax in nearly every state, and a 1099-K showing gross payment amounts that differ significantly from the actual taxable income. Under the Supreme Court’s Wayfair decision (2018) and the subsequent adoption of economic nexus thresholds by nearly every state, online sellers must collect and remit sales tax in states where they meet the threshold (typically $100,000 in sales or 200 transactions). For Amazon FBA sellers, the problem is compounded: Amazon distributes inventory across its fulfillment network, creating physical nexus (through inventory presence) in states that the seller may not even be aware of. On the income tax side, the IRS receives 1099-K forms from payment processors showing gross payments, and the seller must reconcile these amounts with their actual net revenue (after returns, refunds, platform fees, and shipping costs). Failing to properly reconcile the 1099-K with the tax return is one of the most common triggers for IRS notices to online sellers.

✓Key takeaway

E-commerce tax obligations:

Obligation	Trigger	Threshold
Federal income tax	Any business income	All net profit reported on Schedule C, Form 1120, or Form 1120-S
Self-employment tax	Schedule C net income	15.3% on net SE income (92.35%)
Sales tax collection	Economic nexus OR physical nexus in the state	Typically $100,000 in sales or 200 transactions per state
State income tax	Nexus in the state (physical or economic)	Varies by state
1099-K reporting	Payment processor reports gross payments to IRS	$600+ in gross payments (current threshold)

Amazon FBA physical nexus states (where Amazon stores inventory): Amazon operates fulfillment centers in 25+ states. If your inventory is stored in a state’s fulfillment center, you have physical nexus in that state for sales tax purposes (and potentially for income tax).

How do e-commerce sellers handle their taxes correctly?

Hypothetical example

Round numbers. An Amazon FBA seller has the following annual activity:

Revenue and cost reconciliation:

Item	Amount
Gross sales (per Amazon)	$800,000
Returns and refunds	($60,000)
Amazon fees (referral, FBA, storage)	($200,000)
Shipping costs (inbound to Amazon)	($30,000)
Net revenue	$510,000

The 1099-K from Amazon shows $800,000 in gross payments. The tax return must reconcile this:

Line	Amount
Gross receipts (matches 1099-K)	$800,000
Returns and allowances	($60,000)
Cost of goods sold	($250,000)
Gross profit	$490,000
Amazon fees	($200,000)
Shipping costs	($30,000)
Other business expenses	($60,000)
Net profit (Schedule C)	$200,000

If the seller only reports $510,000 as gross receipts (the net amount received), the IRS sees a $290,000 discrepancy between the 1099-K ($800,000) and the reported income ($510,000), which triggers a CP2000 notice.

Inventory and COGS calculation:

Item	Amount
Beginning inventory	$80,000
Purchases during the year	$300,000
Freight-in (shipping to Amazon)	$30,000
Goods available for sale	$410,000
Ending inventory	($160,000)
Cost of goods sold	$250,000

Inventory valuation methods:

Method	How It Works	Best For
FIFO (First In, First Out)	Oldest inventory cost is assigned to COGS first	Rising prices (lower COGS, higher profit)
Weighted average cost	Average cost of all inventory assigned to COGS	Large volume of similar items
Specific identification	Actual cost of each item sold	High-value, unique items
LIFO (Last In, First Out)	Newest inventory cost assigned to COGS first	Falling prices (but not available under IFRS; rarely used by small sellers)

UNICAP rules (IRC 263A): If the seller’s average annual gross receipts exceed $32 million (3-year average, for 2026), the Uniform Capitalization rules require certain indirect costs to be capitalized into inventory:

Costs Capitalized into Inventory	Costs Still Deductible
Warehouse rent	Marketing and advertising
Insurance on inventory	General office expenses
Purchasing department costs	Interest expense (unless IRC 263A(f) applies)
Quality control	R&D expenses
Inbound freight	Selling expenses

For sellers under the $32 million threshold, these indirect costs can be expensed currently.

Sales tax compliance:

State	Nexus Type	Registration Required?
States with FBA warehouses	Physical nexus (inventory stored)	Yes
States with $100K+ in sales	Economic nexus	Yes
States where Amazon collects as marketplace facilitator	Marketplace facilitator law	No registration needed (Amazon collects and remits)

Important: As of 2025, Amazon collects and remits sales tax as a marketplace facilitator in all states that impose sales tax. This means FBA sellers generally do NOT need to collect sales tax themselves on Amazon sales. However:

Platform	Marketplace Facilitator?
Amazon	Yes (collects and remits in all states)
eBay	Yes
Etsy	Yes
Walmart Marketplace	Yes
Shopify (own website)	No (seller must collect and remit)
Own website (non-marketplace)	No (seller must collect and remit)

If the seller also has their own Shopify store, they must register for sales tax collection in every state where they have nexus (physical or economic) and collect/remit sales tax on those sales.

Key deductions for e-commerce sellers:

Deduction	Details
Amazon fees (referral, FBA, storage, advertising)	Fully deductible business expense
Product photography	Deductible
Packaging materials	Part of COGS or deductible supply expense
Home office (if applicable)	Simplified ($5/sq ft, max 300 sq ft = $1,500) or actual method
Software (inventory management, accounting)	Deductible
Product samples	Deductible (or COGS if used for testing)
Returns processing costs	Deductible
UPC/barcode costs	Deductible
PPC advertising (Amazon, Google, social)	Fully deductible
Product liability insurance	Deductible
Travel to supplier/trade shows	Deductible

Entity structure for e-commerce:

Revenue Level	Recommended Entity	Why
Under $50,000 net profit	Sole proprietorship (Schedule C)	Simple; low cost
$50,000-$100,000 net profit	Single-member LLC	Liability protection; no change in tax treatment
Over $100,000 net profit	S-Corp election (LLC or corporation)	SE tax savings of $5,000-$15,000+/year
High growth / seeking investors	C-Corp (for QSBS if applicable)	QSBS 100% gain exclusion on exit

S-Corp SE tax savings example:

Item	Schedule C	S-Corp
Net profit	$200,000	$200,000
Reasonable salary	N/A	$80,000
S-Corp distribution	N/A	$120,000
SE tax / payroll tax	$28,270 (15.3% on 92.35%)	$12,240 (on $80,000 salary)
SE tax savings		$16,030

Illustrative numbers only, not a real client and not advice for your facts.

Related guides:

Tax Planning for Amazon FBA Sellers: Inventory Accounting, Multi-State Nexus, Sales Tax, and Cost of Goods Sold

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Cite this page

Yarik Yarosh, CPA. "Tax Planning for E-Commerce and Amazon FBA Sellers: Inventory, Nexus, and Multi-State Sales Tax." Blue Cloud CPA, September 5, 2026, updated October 4, 2026. https://bluecloudcpa.com/guides/small-business-tax-planning-ecommerce-amazon-fba-sellers

This guide is general information, not tax advice for your specific situation. Which points apply, and how, depends on your facts.