The E-commerce Due Diligence Checklist (2026)

E-commerce businesses can look great on a dashboard and still be fragile underneath. Revenue is easy to see; what's hard — and what diligence is for — is finding out how durable that revenue is. A DTC brand that depends on one ad channel, one platform, or one supplier can unwind fast after close, and the margins are often thinner than the top line suggests once shipping, returns, and ad spend are counted honestly.

This is a practical e-commerce due diligence checklist: what to verify before you close, and the red flags specific to online retail. It builds on the general M&A due diligence checklist with the items unique to e-commerce.

What makes e-commerce diligence different

Two things drive it: dependency risk (on platforms, channels, and suppliers the buyer doesn't control) and true margin (what's actually left after the costs that don't show up in a simple P&L line). Most e-commerce surprises after close come from one of those two places.

1. Revenue quality and channel mix

• ✓Revenue by sales channel — owned site (Shopify/WooCommerce) vs. marketplaces (Amazon, Etsy). A business that's 90% Amazon is exposed to one platform's account-suspension and fee decisions.
• ✓Revenue by product — concentration in one or two SKUs is a risk if a supplier, trend, or listing disappears.
• ✓Reconcile to deposits — tie reported revenue to the platform payout reports and bank deposits, net of refunds and chargebacks. Gross merchandise value is not revenue.

2. Customer economics and retention

• ✓Repeat purchase rate and customer LTV — a brand with real repeat purchasing is far more valuable than one buying every sale with ads.
• ✓New vs. returning revenue split — heavy reliance on new customers means you're renting growth from ad platforms.
• ✓Email/SMS list health — list size, engagement, and what share of revenue comes from owned channels (flows, campaigns) vs. paid acquisition.

3. Marketing and acquisition dependency

This is the e-commerce deal-killer to check early:

• ✓Blended ROAS and MER (marketing efficiency ratio) — across all channels, not the cherry-picked campaign numbers.
• ✓Customer acquisition cost trend — is CAC rising over time? Most DTC margins erode here.
• ✓Channel concentration — if 70%+ of new customers come from one ad platform, a CPM spike or account issue hits the whole business.
• ✓Organic vs. paid — how much demand exists without paid spend (branded search, direct, SEO)?

4. True margins

• ✓Gross margin after landed COGS — product cost plus freight, duties, and inbound shipping.
• ✓Contribution margin after shipping, fulfillment, returns, and payment fees — outbound shipping and a real returns rate often turn a "healthy" gross margin into a thin contribution margin.
• ✓Discount and promotion dependency — is the business profitable at full price, or only when it's running a sale?

5. Inventory and working capital

• ✓Inventory valuation and aging — how much is current, sellable stock vs. slow-moving or obsolete?
• ✓Working capital cycle — cash tied up in inventory and the gap between paying suppliers and getting paid. Underestimating this is how buyers get squeezed right after close.
• ✓Inventory in the sale — what's included, at what value, and who verifies the count.

6. Suppliers and operations

• ✓Supplier concentration and contracts — single-source suppliers, minimum order commitments, and what transfers on a change of control.
• ✓Fulfillment — in-house, 3PL, or dropship, and the cost and reliability of it.
• ✓Manufacturing/lead times — exposure to a single factory or region.

7. Brand, legal, and digital assets

• ✓Trademarks and IP — owned brand assets, and any pending disputes.
• ✓Reviews and reputation — review velocity and sentiment across the site and marketplaces; a recent decline is a flag.
• ✓Digital assets transfer — domain, store admin, ad accounts, email platform, and social handles must transfer cleanly. Ad-account history especially can be hard to move.
• ✓Compliance — product liability, claims/labeling, and data-privacy handling.

E-commerce-specific red flags

• ✓Revenue concentrated on a single platform (e.g., almost all Amazon) or a single SKU.
• ✓New-customer revenue dependent on one ad channel with a rising CAC.
• ✓Healthy gross margin that collapses to a thin contribution margin after shipping and returns.
• ✓A real returns rate the seller doesn't volunteer.
• ✓Slow-moving or obsolete inventory padded into the sale value.
• ✓Single-source suppliers with no backup and unfavorable change-of-control terms.

Where the time goes — and how to compress it

Most e-commerce diligence is reconciling and reading: platform payout reports, ad-account exports, supplier agreements, inventory reports, and a data room of PDFs — cross-checking each claim against the underlying numbers. It's slow, and the costs that matter most (returns, shipping, real CAC) are the easiest to gloss over.

This is the part you can systematize. Deal OS reads the documents in a deal workspace and produces source-cited diligence briefs and findings — every claim quoted from your own documents and verified before you see it — plus risk, contradiction, and missing-information audits across the data room. It doesn't replace your judgment or your advisors; it gets you to the questions that matter faster. See how we approach diligence automation for the document-heavy review specifically.

Frequently asked questions

What is the most important thing to check when buying an e-commerce business? Dependency and true margin. Check how concentrated revenue is on a single platform, channel, or SKU, and recalculate contribution margin after shipping, returns, fulfillment, and payment fees — the costs that turn a healthy-looking gross margin into a thin real one.

How do you verify revenue for an e-commerce acquisition? Reconcile reported revenue to the platform payout reports (Shopify, Amazon, etc.) and bank deposits, net of refunds and chargebacks. Gross merchandise value isn't revenue, and a returns rate the seller doesn't volunteer is a common source of overstatement.

What are the biggest red flags in an e-commerce acquisition? Revenue concentrated on one platform or SKU, new customers dependent on a single ad channel with rising CAC, gross margins that collapse after shipping and returns, obsolete inventory padded into the sale, and single-source suppliers with weak change-of-control terms.

Can AI help with e-commerce due diligence? Yes, for the document-heavy parts. Tools like Deal OS read the supplier agreements, financials, and data-room documents and produce source-cited findings and contradiction audits, so you reach the real questions faster. It supports your diligence; it doesn't replace your own verification or professional advisors.

Review your next e-commerce deal with less grind

If reconciling the payout reports and reading the supplier contracts is eating your nights, book a 15-minute walkthrough of how Deal OS turns a workspace of documents into cited diligence findings.