Sales tax filings come down to documentation. If your records can’t show what you sold, where, and how much tax was collected, you can’t defend the numbers on your returns. Ecommerce sellers need cleaner records than most businesses because sales happen across multiple states, platforms, and tax rules at once.

Start with sales by state. Every state where you have nexus needs its own breakdown showing gross sales, taxable sales, exempt sales, and tax collected. Economic nexus thresholds vary, so you also need totals for states where you’re close to triggering a filing requirement. Without state-level detail, you can’t file accurately and you can’t tell when a new state needs to be added.

Separate marketplace sales from direct sales. Marketplaces like Amazon, Etsy, and Walmart collect and remit sales tax on your behalf in most states under marketplace facilitator laws. Those sales still need to be reported on your returns in many states, just as non-taxable or already-collected sales. Direct sales through Shopify, WooCommerce, or your own site are your responsibility to collect and remit. Mixing them together creates filings that overpay or underpay.

Keep tax collected amounts tied to each transaction. The tax you collect is not revenue. It’s a liability you hold until you remit it. Your books should show tax collected as a separate liability account, not buried in sales income.

Save exempt and resale certificates for every customer claiming exemption. If you sell wholesale or to nonprofits, you need a valid certificate on file before you skip collecting tax. States can come back years later asking for proof. No certificate means you owe the tax yourself.

Track refunds and returns carefully because they reduce taxable sales and the tax you owe. If you refunded a customer in a later filing period, you need to adjust the right state’s return.

Shipping charges are taxable in some states and not in others. Your records should separate shipping revenue from product revenue so the right portion gets taxed in each jurisdiction.

Pull TaxJar reports monthly and reconcile them against platform payout reports from Shopify, Amazon, Stripe, and any other channel you use. The payout reports show what actually hit your bank. TaxJar shows what should have been collected. Differences point to setup issues or missed transactions.

Most ecommerce sellers benefit from sales tax management that handles the monthly reconciliation between platforms and filing software. The work of compiling state-by-state numbers, matching payouts to sales, and tracking exemption certificates is where mistakes happen. A firm offering bookkeeping, tax, and consulting services built for ecommerce keeps these records organized throughout the year so filings are routine instead of a scramble each month.