Filing sales tax returns is one of the most important compliance responsibilities for any US business selling taxable goods or services. Before you file, you need to understand two foundational concepts: first, what sales tax is and why the US system is so state-specific; and second — critically — whether you even have nexus in the states where you plan to file. Filing in a state where you have no nexus is unnecessary. Failing to file where you do have nexus is a compliance violation.
Step 1: Confirm Your Nexus
You are only required to collect and remit sales tax in states where you have nexus. Physical nexus comes from having a store, warehouse, employees, or inventory in a state. Economic nexus — established by the 2018 Wayfair ruling — is triggered when you exceed a state’s sales threshold, typically $100,000 in annual sales or 200 transactions. Read our complete guide to sales tax nexus to determine exactly which states you have an obligation in before you begin registration.
Step 2: Register for a Sales Tax Permit
Each state requires you to register and obtain a sales tax permit (also called a seller’s permit or certificate of authority) before collecting tax. Registration is free in most states. You will provide your business name, EIN, address, business type, and an estimate of monthly tax liability. California’s CDTFA, the Texas Comptroller, New York’s Department of Taxation and Finance, and Florida’s Department of Revenue all offer online registration through their respective portals.
Step 3: Collect the Right Rate
Once registered, you must collect the correct combined rate from each customer. Most states use destination-based sourcing — meaning you charge the rate applicable to the buyer’s location. A few states use origin-based sourcing. Getting this wrong on thousands of transactions is one of the most common and expensive sales tax mistakes businesses make. Use our calculator to look up any US location’s exact combined rate. Our step-by-step calculation guide also covers origin vs. destination sourcing in detail.
Step 4: Track and Organize Your Data
Maintain detailed records of all sales, tax collected per transaction, exempt sales, and resale certificate numbers. Organize records by state if you have multi-state nexus. Retain all records for at least four years (some states require longer). Disorganized records are a leading contributor to audit exposure — particularly in California, New York, and other states with aggressive audit programs.
Step 5: File Your Return
Filing frequency is assigned when you register: monthly for larger businesses, quarterly or annually for smaller ones. All major states now have online filing portals. Your return will ask for total gross sales, taxable sales, exempt sales, sales tax collected, and any credits or adjustments. Due dates are typically the 20th of the month following the reporting period. Late filing and late payment both trigger penalties and interest — avoiding these is the core reason to understand the mistakes that cause businesses to miss deadlines.
Step 6: Remit Payment
Pay the tax collected when you file. Most portals accept ACH bank transfer or credit card. If you have overpaid in prior periods, you may be able to claim a credit on the current return. Note that the sales tax you collect and remit is not your own money — it belongs to the state from the moment the customer pays it. Misusing collected sales tax to cover business cash flow is treated very seriously by state revenue departments.
Sales Tax Automation for Multi-State Sellers
If you have nexus in multiple states, manual compliance becomes impractical quickly. Automation platforms like Avalara, TaxJar, and Vertex integrate with your e-commerce platform or accounting software to handle rate calculation, nexus monitoring, return preparation, and auto-filing. This is especially important for businesses approaching the economic nexus thresholds in multiple states simultaneously. And remember — if you itemize on your personal return, some of these compliance costs may factor into your sales tax deduction.