North Carolina Based · Serving Businesses Nationwide
E-Commerce Accounting and Omnichannel Finance Architecture for Product-Based Businesses
Most e-commerce businesses have bookkeeping. What they don't have is accounting that actually reflects their operations — inventory that reconciles at month-end, COGS that matches what was sold across every channel, and a general ledger that doesn't require three hours of manual spreadsheet work every time Amazon sends a payout. Certum Solutions builds the e-commerce finance architecture that makes all of that automatic.
500+
Businesses served across 15+ industries
15+
Years integrating ecommerce and accounting systems
Multi Award Winner
QuickBooks Solution Provider, top 5% nationally
✔️ Woman-Owned & BBB Accredited
✔️ Accountants Who Speak Tech
✔️ Platform-Agnostic Advisors
✔️ Local Roots, National Reach
What E-Commerce Accounting Actually Requires
E-commerce accounting requires more than tracking income and expenses. It requires real-time COGS calculation across every sales channel, automated reconciliation of marketplace payouts from Amazon, Shopify, and wholesale, accurate inventory valuation tied to your general ledger, and financial statements that reflect what actually sold — not what the bank received two weeks later after platform fees, refunds, and reserves were deducted.
E-commerce integration experts
The E-Commerce Finance Stack Certum Builds
Most product-based businesses end up with the same problem: their operations live in one system, their inventory in another, and their accounting somewhere else. None of them talk to each other cleanly. Month-end becomes a manual reconciliation project, and the P&L is always slightly wrong because the inventory and the books never quite agree.
The e-commerce finance stack Certum builds has three integrated layers:
The inventory layer
The inventory layer — Cin7 Core, Cin7 Omni, or Katana MRP — becomes the single source of truth for what you have, where it is, what it cost to get there, and what it sold for. Every purchase order, warehouse movement, sales order, and fulfillment event flows through the inventory system before it touches the ledger.
The reconciliation layer
The reconciliation layer connects your sales channels — Shopify, Amazon, wholesale portals, and any other platform — to the inventory system and to your accounting software. Instead of recording individual transactions at the point of sale, the system batches them intelligently: gross sales, platform fees, returns, and payment processor adjustments flow into the ledger as structured journal entries that match your bank deposits exactly.
The accounting layer
The accounting layer — QuickBooks Online, Xero, or another platform — receives clean, reconciled data from the two layers above it. Your chart of accounts is structured to produce channel-level revenue, SKU-level COGS, and location-level margin reporting without manual intervention. Month-end close takes hours, not days.
The Bigger Picture
Multi-Channel Reconciliation — Amazon, Shopify, and Wholesale Under One Ledger
The most common e-commerce accounting failure is treating each sales channel as a separate bookkeeping problem. Amazon sends bi-weekly payouts that bundle gross sales, advertising costs, storage fees, returns, and reserve holds into a single deposit that bears no relationship to actual revenue. Shopify sends net payouts that strip out processing fees before the money hits the bank. Wholesale orders have payment terms, partial payments, and returns that sit in accounts receivable for 30 to 90 days.
Standard bookkeepers record the deposit. That is not accounting. Accurate e-commerce accounting breaks every payout down into its components — gross revenue recognized at the point of sale, COGS recorded when goods are shipped, fees expensed in the period they occurred, and refunds matched back to the original transaction. Certum configures the systems and chart of accounts to make this happen automatically, so your P&L reflects what you earned, not what landed in the bank.
For businesses selling across multiple channels simultaneously, we build a unified ledger structure that shows consolidated revenue alongside channel-level detail — Amazon vs. Shopify vs. wholesale vs. retail — without requiring separate QuickBooks files or manual allocation worksheets.
Systems We Work With
E-Commerce Platforms and Inventory Systems We Connect
Shopify
Certum configures Shopify to pass structured sales, refund, and payout data to your inventory system and accounting platform, eliminating the manual reconciliation that typically consumes 3–5 hours per week. We handle both direct-to-consumer and Shopify wholesale channels, including proper revenue recognition for deferred orders and gift card liabilities.
Cin7 Core and Cin7 Omni
As a certified Cin7 implementation partner, Certum configures Cin7 as the operational hub for inventory, purchase orders, sales orders, and fulfillment — with a bi-directional sync to QuickBooks Online or Xero that keeps your ledger accurate without duplicate data entry. We handle multi-location inventory, B2B and B2C channels simultaneously, and all the nuances of how Cin7 maps to chart of accounts codes for COGS, landed cost, and inventory valuation.
QuickBooks Online
Certum is an Intuit Elite ProAdvisor (top nationally) and configures QuickBooks Online as the accounting backbone for e-commerce operations — including the chart of accounts structure, class and location tracking for channel-level reporting, and the integration settings that allow Cin7, Katana, Shopify, and Amazon data to flow in cleanly. We also handle the transition from cash-basis to full accrual accounting that most e-commerce businesses need once they cross $500K in revenue.
Katana MRP
For product businesses that build, assemble, or configure their own goods, Certum implements Katana as the production and inventory layer — connecting bill-of-materials management, production orders, and raw material tracking directly to your accounting system so COGS is calculated from actual inputs, not estimates. We handle the Katana-to-QuickBooks sync including work-in-progress valuation, finished goods inventory, and manufacturing variance reporting.
Xero
As a Xero Bronze Partner, Certum implements and configures Xero for e-commerce businesses that prefer its interface or have outgrown QuickBooks — including the integration with Cin7 or Katana, the reconciliation rules for marketplace payouts, and the tracking category structure that enables channel-level reporting without separate ledgers. We handle migrations from QuickBooks to Xero including historical data preservation and cutover testing.
When Systems Don’t Talk to Each Other
Inventory errors, fulfillment delays, and reporting gaps often stem from disconnected systems. Technology Consulting identifies integration gaps and automation opportunities.
Built for the Middle Band of Growing Businesses
For businesses between $1M and $50M, eCommerce systems & integration are rarely about “installing software.” It is about aligning systems with real operational complexity. We specialize in ecommerce businesses that have outgrown spreadsheet reconciliation and need integrated inventory, purchasing, landed cost tracking, and accurate COGS reporting.
Our typical clients:
✔️ Generate between $1M and $50M annually
✔️ Need stronger financial reporting and system discipline
✔️ Feel caught between DIY tools and Big 4-style firms
We serve as the bridge between early-stage bookkeeping and full ERP environments; stabilizing systems today while guiding smart transitions tomorrow.
Who This Is For
Signs Your E-Commerce Books Are Breaking Down
Most businesses have to hire three different vendors to get what Certum Solutions delivers in one engagement: a bookkeeper for day-to-day work, a consultant to implement software, and a support partner to keep it running. That fragmented model creates finger-pointing when things go wrong.
✓ Your COGS on the P&L doesn't match your actual cost of goods sold when you manually calculate it
✓ Amazon payouts don't reconcile to the revenue line in QuickBooks without significant manual adjustment
✓ You can't see profitability by channel — Amazon vs. Shopify vs. wholesale are all pooled together
✓ Inventory on your balance sheet doesn't match the physical count or the number in your inventory system
✓ Month-end close requires someone to manually pull reports from three or four different platforms and combine them in a spreadsheet
✓ Your accountant or bookkeeper is recording bank deposits rather than actual transactions — and your books are cash-basis even though you carry inventory
✓ You've added sales channels and the accounting complexity has outpaced whatever system you set up originally
✓ You know the books are wrong but you're not sure where the errors are coming from
Our Process
How We Set Up E-Commerce Accounting
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Step 1: Current State Audit
Before we configure anything, we audit your current sync setup, chart of accounts structure, inventory system data quality, and reconciliation gaps. We identify where the errors are originating — usually in the connection between the inventory system and the accounting platform, or in how marketplace payouts are being recorded — and document the full scope of work before any changes are made.
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Step 2: Inventory System as Source of Truth
We configure your inventory system — Cin7 or Katana — as the operational hub. Every purchase order, stock movement, sales order, and fulfillment event runs through the inventory system first. This ensures that COGS is calculated based on actual inventory movements rather than estimated or manually entered figures, and that your balance sheet inventory value matches the physical count.
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Step 3: Chart of Accounts for Channel-Level Reporting
We rebuild or restructure your chart of accounts in QuickBooks Online or Xero to support the reporting your business actually needs — revenue by channel, COGS by product category, landed cost as a component of inventory value, and platform fees as a separate expense line rather than buried in cost of goods. We configure Classes or Location tracking in QuickBooks to enable channel-level P&Ls without separate company files.
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Step 4: Automated Reconciliation Configuration
We configure the integration layer between your sales channels and your accounting platform — whether that's the native Cin7-QuickBooks sync, A2X for Amazon and Shopify, or a combination of tools — so that marketplace payouts flow into the ledger as structured journal entries that match your bank deposits. We test the reconciliation against three months of historical data before go-live to confirm accuracy.
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Step 5: First Month-End Close Verification
We complete the first month-end close alongside your team, verifying that inventory reconciles to the balance sheet, that channel-level revenue is accurate, that COGS is correctly calculated, and that the bank reconciliation clears without manual adjustment. We document the close process in a written SOP so your team can repeat it independently going forward.
Trusted by Businesses Across Industries
FAQ
Frequently Asked Questions — E-Commerce Accounting and Inventory Integration
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Shopify and Amazon reconciliation requires breaking each marketplace payout into its components — gross sales, platform fees, returns, payment reserves, and advertising costs — and recording them as structured journal entries in QuickBooks rather than recording the net bank deposit. For Shopify, the native integration or A2X handles this automatically. For Amazon, A2X or a manual settlement reconciliation process maps each line of the settlement report to the correct QuickBooks account. Certum configures and tests this reconciliation for e-commerce businesses as part of our inventory accounting integration service.
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For e-commerce businesses using QuickBooks Online, the two most common inventory system choices are Cin7 (Core or Omni) and Katana MRP. Cin7 is best for multi-channel retailers and wholesalers who need order management, purchase orders, and real-time stock tracking across Amazon, Shopify, and wholesale channels simultaneously. Katana is best for businesses that build or assemble their own products and need bill-of-materials management and production tracking connected to the ledger. Both platforms integrate directly with QuickBooks Online via a bi-directional sync. The right choice depends on your fulfillment model, product complexity, and channel mix — Certum assesses this during a free discovery call.
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QuickBooks Online handles accounting well but is not designed to manage operational inventory at scale. If you are managing more than a few hundred SKUs, selling across multiple channels, or building and assembling products, QuickBooks inventory will create reconciliation problems — items going negative, COGS being miscalculated, and inventory on the balance sheet that doesn't match reality. Cin7 or Katana sits above QuickBooks as the operational inventory layer and passes clean, reconciled data to the accounting platform. Many businesses try to run on QuickBooks inventory alone until the errors become expensive enough to force a change — the cleaner path is to configure the right inventory system before the problems compound.
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Automatic COGS calculation for multi-channel sellers requires an inventory system that tracks the landed cost of every unit from purchase to sale — including freight, customs, and storage — and passes a COGS journal entry to the accounting platform each time a unit is sold. When Cin7 is configured correctly as the inventory hub, it calculates COGS at the moment of fulfillment using FIFO, weighted average, or standard costing depending on your business model, and syncs the journal entry to QuickBooks or Xero automatically. The key requirement is that every inventory purchase flows through the inventory system before reaching the ledger, so the cost data is accurate when the sale is recorded.
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Yes. Certum configures a single chart of accounts and inventory system structure that handles wholesale and direct-to-consumer sales simultaneously — with channel-level revenue tracking that shows each stream separately on the P&L without requiring separate company files or manual allocations. Cin7 Omni is particularly well-suited for businesses operating both channels because it manages B2B pricing, purchase order processing, and wholesale fulfillment workflows alongside DTC e-commerce operations in a single platform. We configure the integration so that both channels flow into QuickBooks or Xero with correct revenue recognition, COGS, and accounts receivable handling for wholesale payment terms.
Let’s Streamline Your Ecommerce Back End
From sales to fulfillment to reconciliation, we help eCommerce brands operate with confidence; and scale with strategy.