A state tax number is an identifier a state government assigns to your business so it can track the state taxes you collect, withhold, or owe. You need one whenever your business sells taxable goods or services in a state, hires employees there, or does enough business in the state to cross its economic nexus threshold. It is separate from your federal Employer Identification Number, and a single business operating in multiple states often ends up with several state tax numbers on top of one EIN.
What the Term Actually Covers
“State tax number” is an umbrella label. Depending on what your business does, a state may issue you one identifier or several, each tied to a different tax:
- Sales tax permit (or seller’s permit): authorizes you to collect sales tax from customers on taxable transactions and remit it to the state.
- State employer withholding account: used to withhold and remit state income taxes from employee wages.
- State unemployment insurance account: tracks your contributions to the state’s unemployment fund, administered by the state workforce or labor agency rather than the revenue department.
A retail store with employees would typically hold all three. A freelance consultant with no employees and no taxable product sales might not need any of them. The names and issuing agencies vary by state, but the underlying purpose is the same: the state needs a way to tie your tax payments back to your business.
When Your Business Needs One
Whether you need to register comes down to what your business does and where it does it. The SBA identifies income taxes and employment taxes as the two most common state tax obligations for small businesses.1U.S. Small Business Administration. Get Federal and State Tax ID Numbers
You Sell Taxable Goods or Services
If you sell tangible products at retail, you need a sales tax permit in every state where you have a taxable presence. Five states have no statewide sales tax: Alaska, Delaware, Montana, New Hampshire, and Oregon. Businesses operating exclusively in those states can skip this step. In the other 45 states and Washington, D.C., selling without a permit means you’re either collecting money you have no authority to collect or failing to charge tax you were required to collect.
Services are trickier. Most states tax tangible goods by default, but taxability of services depends heavily on the state and the type of service. Some states tax a narrow list; others tax nearly everything. Check your state’s revenue department before assuming your service business is exempt.
You Hire Employees
Bringing on even one employee usually triggers two separate state registrations. You need a withholding account to deduct state income tax from paychecks, and an unemployment insurance account to fund unemployment benefits. Withholding is typically handled by the state’s revenue or tax department; unemployment goes through the state’s workforce or labor agency. Each issues its own account number.
State thresholds for unemployment insurance registration vary, so you’ll need to check with your state’s workforce agency for the exact trigger.
Eight states impose no individual income tax: Alaska, Florida, Nevada, New Hampshire, South Dakota, Tennessee, Texas, and Wyoming. Businesses operating exclusively in those states won’t need a state withholding number for wages, but they still need unemployment insurance registration, since every state runs its own unemployment program.
You Operate in a Regulated Industry
Businesses dealing in fuel, tobacco, alcohol, cannabis, or other heavily regulated products typically need separate excise tax registrations, each with its own account number and filing requirements. A standard sales tax permit won’t cover those obligations.
Out-of-State Sales and Economic Nexus
You don’t need a physical location in a state to owe sales tax there. In its 2018 decision in South Dakota v. Wayfair, Inc., the Supreme Court overruled the older rule that had required physical presence before a state could impose tax collection duties on a seller.2Supreme Court of the United States. South Dakota v. Wayfair, Inc., No. 17-494 The South Dakota law at issue applied to sellers delivering more than $100,000 in goods or services into the state, or completing 200 or more separate transactions there, in a single year. Every state with a sales tax has since adopted some version of this economic nexus standard.
Most states set their threshold at $100,000 in annual sales, though a handful set it higher. The 200-transaction test has been fading, with many states repealing it and keeping only the dollar-based trigger. If you sell online and ship across state lines, this rule determines how many state tax registrations you may need. A business with $100,000 in sales spread across 15 states could owe registration in every one of them.
What Marketplace Sellers Should Know
If you sell through a major online marketplace like Amazon, Etsy, or Walmart, the platform is likely collecting and remitting sales tax on your behalf. Every state with a sales tax has enacted marketplace facilitator laws that shift the collection duty from individual sellers to the platform.
That doesn’t cover everything. Sales you make through your own website, at trade shows, or from a physical location aren’t handled by the marketplace’s collection. You’d still need your own sales tax permit for those channels. Marketplace facilitator laws only reach transactions that flow through the platform; anything you sell directly remains your responsibility.
How a State Tax Number Differs from an EIN
The most common point of confusion is between a state tax number and a federal Employer Identification Number. They serve different governments and different purposes.
An EIN is a nine-digit number assigned by the IRS for federal tax filing and reporting.3Internal Revenue Service. About Form SS-4, Application for Employer Identification Number You use it on federal income tax returns, federal employment tax filings, and when opening business bank accounts. A state tax number is issued by a state agency for state obligations like collecting sales tax, withholding state income tax, or paying into the state unemployment fund.
Most businesses with employees need both, and the systems run in parallel. Your EIN goes on federal payroll filings and Form 940 for federal unemployment tax. Your state withholding number goes on state wage reports. Your state unemployment number goes on state unemployment filings. Registering for one does not register you for any of the others.4Internal Revenue Service. Employer Identification Number
How to Apply
The process varies by state, but the SBA notes that getting a state tax ID follows a similar pattern to getting a federal one.1U.S. Small Business Administration. Get Federal and State Tax ID Numbers
Most states let you register online through the revenue department’s website. You’ll typically need your federal EIN (or Social Security Number for sole proprietors), your business entity type, ownership details, the business’s physical and mailing addresses, and a description of your business activities. Some states use an interactive wizard that asks about your activities and tells you which registrations apply.
Online applications often produce a tax number within minutes or a few business days. Paper applications still exist in most states but can take several weeks. Registration is free in many states, though some charge modest filing fees. A small number of states require new or higher-risk businesses to post a surety bond as a condition of receiving a sales tax permit, with the bond guaranteeing you’ll remit what you collect. Bond amounts vary based on projected tax liability.
If you need to register in more than one state, expect to repeat the process for each. There’s no single federal portal for state registrations.
What You’re Signing Up For
Holding a state tax number is an ongoing commitment, not a one-time filing.
Collecting and Remitting
With a sales tax permit, you must charge the correct rate on every taxable transaction and remit collected amounts by the state’s deadline. Sales tax you collect doesn’t belong to your business. States treat it as money held in trust for the government, and using it for business expenses instead of remitting it creates serious legal exposure. The same logic applies to state income tax withheld from employee paychecks.
Filing on a Set Schedule
States assign a filing frequency — monthly, quarterly, or annually — based on how much tax your business collects. Higher-volume businesses file monthly; lower-volume businesses may file quarterly or annually. Thresholds vary by state, and as your sales grow the state may move you to a more frequent schedule. Even in periods where you owe nothing, most states still require a “zero return” confirming you had no taxable activity.
Keeping Records
Retain detailed records of every taxable sale, the tax collected, and the amounts remitted. Most states can audit your books going back at least three years, and further if they suspect fraud. If you can’t show that the numbers on your returns match your actual transactions, you’ll owe whatever the state estimates, which rarely favors you.
Use Tax on Business Purchases
One obligation catches many owners off guard. If you buy supplies, equipment, or inventory from an out-of-state vendor that doesn’t charge your state’s sales tax, you generally owe use tax on those purchases. If you already hold a sales tax permit, you typically report and pay use tax on the same return. If you don’t hold a permit but make substantial untaxed purchases, some states require a separate use tax registration.
What Happens If You Skip Registration
Operating without required state tax registrations is not a gray area. States enforce compliance through penalties, interest, and in extreme cases criminal prosecution. Common penalty structures include a percentage-based charge for late filing (often around 10 percent of the tax due), additional penalties for knowingly operating without a permit (which can reach 50 percent of taxes owed in some states), and interest running from the original due date. Where a state determines a business intentionally evaded tax, fraud penalties and criminal charges become possible.
Sales tax exposure can also reach you personally. Because sales tax is money you collect from customers on the state’s behalf, most states treat it as a trust fund obligation. If a business collects sales tax and fails to remit it, the state can pursue corporate officers, directors, and anyone with authority over tax compliance as individuals. This applies even to LLCs and corporations.
Successor liability is a related trap for anyone buying an existing business. Most states make the purchaser responsible for the seller’s unpaid state tax debts regardless of what the purchase agreement says. Request a tax clearance certificate from the state’s revenue department before closing to confirm whether the seller has unresolved liabilities.
Closing a State Tax Account
When you shut down, sell, or restructure a business, formally close each state tax account. The SBA recommends handling final income tax and sales tax returns and notifying both federal and state tax agencies.5U.S. Small Business Administration. Close or Sell Your Business The typical process is to file all outstanding returns (including a final return marked as such), remit any remaining tax owed, and submit a request to close or deactivate each account. Most states allow this online, by phone, or by written request.
Closing an account does not erase existing debts. If you owe back taxes, the state will continue collection regardless of account status. Don’t leave an unused account open either. Some states continue to expect filings from open accounts, and missing them generates penalties even if the business has no activity. Close every account you no longer need, and keep records confirming the closure date and method.