The Best E-Commerce CPA & Accounting Firms in New Jersey (2026): An Honest Seller's Comparison

Who wrote this — and why you should still trust it. This guide is published by ProAxis Tax & Accounting Services, a licensed CPA firm in Bergen County with an e-commerce practice. Yes, we include ourselves. The deal: every firm below is real, independently established, and described only with facts from its own public materials. We say who each firm is best for — including when that is not us. No firm paid to be listed.

E-commerce accounting breaks the ordinary small-business pattern. The deposit that lands in your bank is not your revenue. It is gross sales minus platform fees, refunds, shipping, and ad spend, netted before you ever see it.

Get that reconciliation wrong and every downstream number is wrong too. This guide compares four NJ firms that publicly specialize in online sellers.

How we chose

• E-commerce depth. A dedicated e-commerce practice or service line — not one line in a services list.
• Fit by seller type. An FBA seller, a Shopify brand, and a multi-marketplace operation need different firms.
• Verifiable claims. Everything below comes from each firm’s own website, checked July 26, 2026.
• New Jersey presence. Every firm here has a New Jersey office and serves NJ sellers.

Why this list is short. We applied the same test we use in our other niche guides: does the firm publish a real e-commerce service line? Very few New Jersey firms do. Several well-regarded NJ firms were excluded simply because they list retail generally without an e-commerce practice. We would rather publish four honest entries than pad the list.

Quick comparison

1. ProAxis Tax & Accounting Services — best for monthly books plus nexus monitoring

Our firm. See the disclosure at the top — judge us by the criteria.

ProAxis reconciles platform payouts to gross sales rather than booking the net deposit, so revenue, fees, and refunds each land where they belong. Inventory and cost of goods sold are tracked as stock moves through fulfillment centers. Bookkeeping pricing is published openly instead of quoted on request.

On compliance, the firm tracks economic nexus across states as thresholds move, and handles 1099-K reconciliation against your own books. The firm is licensed in New Jersey and New York.

Choose ProAxis if: you sell on one or more platforms, want monthly numbers you can act on, and want nexus watched continuously rather than discovered at filing time. Look elsewhere if: you need heavy operational registration work in many states at once (see Demian).

2. Monaco CPA — best for Amazon FBA and inventory costing

Gregory Monaco, CPA LLC, doing business as Monaco CPA, is based in Livingston. Its e-commerce page publishes sales tax nexus analysis, Amazon FBA accounting, inventory accounting, and quarterly tax planning. Named capabilities include economic nexus review, multi-platform income reconciliation across Amazon, Shopify, eBay, Etsy and TikTok Shop, FIFO and LIFO inventory costing, and 1099-K reconciliation.

Two published limits are worth knowing before you call. The firm states it accepts NJ-resident engagements only, and that its sales-tax work is limited to nexus analysis and NJ compliance, with other-state operational work coordinated through specialists.

Choose Monaco if: you are a New Jersey resident running FBA and want inventory costing method decisions made deliberately.

3. Demian & Company, LLC — best for established brands filing in many states

Demian & Company, LLC has offices in Cranford and East Brunswick. Its e-commerce page publishes sales tax compliance and multi-state filings, platform-specific bookkeeping across Amazon, Shopify, WooCommerce, Stripe and PayPal, tax planning and preparation, outsourced accounting and CFO services, financial reporting, and marketplace facilitator compliance guidance.

The firm states it serves marketplace sellers, direct-to-consumer brands, dropshipping businesses, and global e-commerce brands, and publishes that it has operated since 1995.

Choose Demian if: you have crossed into many states and want multi-state filing handled operationally, not just advised on.

4. KRS CPAs, LLC — best for multi-marketplace sellers wanting SKU-level reporting

KRS CPAs in Paramus publishes an e-commerce practice built around four problems: finding transactional data, tracking inventory and cost of goods sold, calculating sales tax on online sales, and reducing foreign and platform transaction costs.

Named deliverables include recording sales and reconciling payments across channels, preparing sales and cost of sales by SKU, and tracking nexus in all states. The firm states it works with clients selling through Walmart, Amazon, eBay, Rite Aid, OCM, and Shopify, and serves both start-up entrepreneurs and seasoned store owners.

Choose KRS if: you sell across several marketplaces and want profitability reported per SKU, not just per channel.

How to actually decide

Ask every candidate three seller-specific questions. Will you reconcile my payouts to gross sales and fees, or book the deposit? How do you track inventory and cost of goods sold across fulfillment centers? Who watches my nexus thresholds, and how often? Firms without an e-commerce practice answer the first question with the deposit.

Sequence matters here. Nexus is cheapest to fix before you have been over a threshold for a year. Inventory method is chosen, not discovered. If a firm only looks at your numbers in March, both decisions have already been made for you.

For the broader vetting framework, see How to Choose a CPA in Bergen County NJ and our county-wide comparison of the best CPA firms in Bergen County. Selling from outside North Jersey? See our statewide guide to the best NJ CPA firms for small and mid-size companies, compared region by region. For what seller bookkeeping covers month to month, see Bookkeeping for E-Commerce. For fee benchmarks by return type, see CPA cost in NJ.

Frequently asked questions

Who is the best e-commerce CPA in New Jersey?

It depends on your channel mix and how many states you have crossed. For sellers who want monthly books plus ongoing nexus monitoring, ProAxis Tax & Accounting Services (Bergen County, 100% virtual) is a strong fit. For Amazon FBA sellers who need inventory costing depth, Monaco CPA in Livingston publishes an FBA-specific practice. For established brands filing in many states, Demian & Company in Cranford has run since 1995. For multi-marketplace sellers wanting SKU-level reporting, KRS CPAs in Paramus publishes that focus. Disclosure: this guide is published by ProAxis, with comparison criteria stated openly on the page.

Why do so few New Jersey CPA firms specialize in e-commerce?

E-commerce accounting is operationally different from ordinary small-business work. It means reconciling platform payouts to gross sales. It means tracking inventory as it moves through third-party warehouses. It also means watching economic nexus in dozens of states at once. Most general practices are not set up to do that monthly. We checked New Jersey firms publishing a dedicated e-commerce practice in July 2026 and found only a handful. That is why this list is shorter than our other niche comparisons.

How much does an e-commerce CPA cost in NJ?

Most sellers pay for monthly bookkeeping plus annual tax work. Bookkeeping for a solo seller typically runs $300 to $500 per month, and $400 to $700 for a small business under $500K in revenue. Multi-channel sellers between $500K and $2M typically run $700 to $1,400 per month, because each sales channel is a separate reconciliation. Multi-state sales tax registration and filing is usually scoped separately. These are typical published ranges, not an offer; final fees are scoped during an engagement.

Does selling on Amazon create sales tax nexus in other states?

It can, in two separate ways. After South Dakota v. Wayfair (2018), states may impose economic nexus based on sales volume alone, without any physical presence. Separately, inventory stored in a third-party fulfillment warehouse can create physical presence in that state. Marketplace facilitator laws now shift much of the collection duty to the platform. They do not always remove a seller’s own registration or income tax filing duties. The two questions are different and need to be answered separately.

What should an e-commerce seller ask a CPA before hiring?

Ask three things. First, will you reconcile my platform payouts to gross sales and fees, or just book the deposit that hits my bank. Second, how do you track inventory and cost of goods sold across fulfillment centers. Third, who monitors my economic nexus thresholds as they change, and how often. A firm without an e-commerce practice usually answers the first question with the deposit, which understates revenue and hides fees.

This guide is general information, not tax, legal, or accounting advice, and does not create a CPA-client relationship. All third-party firm information comes from public sources — each firm’s own website — as of July 26, 2026, and may change. We are not affiliated with, and received no compensation from, any firm listed. All trademarks and firm names belong to their owners. Verify any firm’s license at CPAverify.org or through the New Jersey Division of Consumer Affairs.