How to Set Up Sales Tax Tracking Across States

Setting up multi-state sales tax tracking is four steps: establish where you have an obligation, register in those states and nowhere else, configure collection correctly on every channel including the ones the marketplace does not cover, and separate the tax collected into a liability account so the money is there when the return is due. Most sellers do the third step, skip the first, and discover the second and fourth during an audit.

This describes how the mechanics generally work. It is not tax advice, the rules are state law and they change, and the specific answer for your business depends on facts that belong in front of a professional or the state’s own department of revenue.

Step 1: Determine where you actually have an obligation

Two things can create one. Physical presence, which includes an office, an employee, or inventory sitting in a warehouse. And economic nexus, which is a threshold of sales volume or transaction count into a state, established for remote sellers after the Supreme Court’s 2018 decision in South Dakota v. Wayfair.

Build a worksheet with one row per state and three columns: gross sales into that state for the trailing twelve months, transaction count into that state, and whether any inventory of yours has been physically located there.

Pull the sales and transaction numbers from each marketplace’s reporting, by ship-to state. Pull inventory location from your fulfillment provider’s placement reports, which for FBA sellers means the inventory event and placement detail reports, since Amazon decides placement and it changes without notice.

Then check each state’s current threshold on that state’s own department of revenue site. Do not use a roundup article. Thresholds have moved repeatedly since 2018, and the direction has mostly been toward dropping the separate transaction-count trigger, which changes the answer materially for high-volume low-price sellers.

Worked example

A seller does $4.2M in annual revenue across Amazon, Shopify, and Walmart. Their state worksheet shows:

• California: $610,000 in sales, 21,400 transactions, FBA inventory present. Obligation on multiple grounds.
• Texas: $340,000, 12,100 transactions, FBA inventory present. Obligation.
• Vermont: $48,000, 1,900 transactions, no inventory. Below most common dollar thresholds, and whether the transaction count matters depends on whether that state still applies one. This is the row that requires an actual check rather than an assumption.
• Wyoming: $9,200, 290 transactions, no inventory. Almost certainly nothing.

The seller’s instinct was that they had obligations in “about forty states.” The worksheet produced eleven. Registering in the other twenty nine would have created twenty nine ongoing filing obligations for no reason, which is a cost people underestimate because it does not show up as tax.

Step 2: Register only where the worksheet says

Registration is not free. It creates a filing obligation that persists whether or not you owe anything, and unfiled zero returns generate notices.

Before registering anywhere you should have been registered previously and were not, stop and get advice. Most states offer some form of voluntary disclosure with a limited lookback and penalty relief, but eligibility usually turns on approaching the state before it contacts you. Registering forward can foreclose that option. This is the highest-stakes decision in the whole process and the worst place to move fast.

Step 3: Configure collection on every channel

Marketplace facilitator laws moved collection and remittance for marketplace sales onto Amazon, Walmart, eBay, and the rest. That covers those channels. It does not cover your own website.

So the configuration splits:

Marketplace channels. Confirm the marketplace is collecting in each state where you are registered, and set your product tax codes correctly. Taxability is not uniform. Clothing, groceries, supplements, and digital goods carry state-specific exemptions, and in at least one state the clothing exemption depends on the price of the garment. The product tax code you assign determines whether the marketplace applies that exemption. Sellers configure these once at launch and never audit them.

Your own storefront. You are responsible here. Configure rates by state, apply the same product tax codes, and confirm the platform is handling destination sourcing correctly for the states that require it.

Filing. Even where the marketplace remits, several states still expect a registered seller to file a return reporting marketplace sales as exempt or deducted. Confirm state by state whether a return is required and what it must show.

Step 4: Separate the money in your books

Sales tax collected is not revenue. It is money held for a state. When a marketplace deposit lands as a single net figure and nobody breaks it apart, the tax collected disappears into sales, revenue is overstated, and the cash that should be reserved gets spent on inventory.

The fix is structural. Tax collected posts to a liability account. Remittances draw that account down. The balance at any moment should approximate what you owe, and if it does not, something upstream is misconfigured.

Doing this by hand from settlement reports is where the process falls apart, because those reports are dense and the discipline lapses in a busy month. The tools built for this problem split the payout into its components automatically. A2X and Link My Books both construct settlement journals that separate tax collected from sales. ConnectBooks handles marketplace settlement reconciliation as part of its accounting sync for sellers running Amazon, Shopify, Walmart, TikTok Shop, and eBay into QuickBooks or Xero. Dedicated sales tax engines approach the same problem from the compliance side instead, calculating rates at checkout and preparing the filings.

Whichever route, the test is the same. Pull a trial balance. If sales tax payable is zero or missing, the separation is not happening.

Keeping it current

Recheck the state worksheet annually, and after any year when sales mix or fulfillment footprint changed. Reconfirm thresholds against the state sites rather than your notes. Re-audit product tax codes when you add a category.

For the federal recordkeeping baseline underneath all of this, IRS Publication 334, Tax Guide for Small Business, sets out what records a business is expected to maintain, and the Small Business Administration publishes general guidance on state obligations for new businesses. Neither answers a nexus question. For that, ask the state or ask a professional, and ask before you act rather than after.