Your sales tax number is on the registration certificate your state issued when you signed up to collect sales tax, on every sales tax return you’ve filed, in the confirmation emails your state sent after each filing, and inside your account on the state revenue department’s website. If none of those turn it up, a phone call to the state tax agency will. The number is state-issued and state-specific, so if you collect in more than one state, you have a separate number for each one, and you find each one the same way inside that state’s system.
Sales Tax Number vs. EIN
Before you start hunting, make sure you’re looking for the right number. Your sales tax number and your federal Employer Identification Number are two different things from two different agencies. The EIN is a nine-digit number the IRS assigns to your business for federal tax purposes. Your sales tax number comes from your state’s department of revenue and authorizes you to collect sales tax in that state. You need both, and they almost never match.
If it turns out you actually need your EIN, check the original IRS confirmation notice (Notice CP 575), your bank records, past federal returns, or call the IRS at 800-829-4933. The IRS won’t reissue a CP 575, but it will send a Letter 147C that serves the same verification purpose.1Internal Revenue Service. Employer Identification Number Corporations, partnerships, and other non-individual entities are required to use an EIN as their taxpayer identification number for federal filings.2Office of the Law Revision Counsel. 26 USC 6109 – Identifying Numbers
Check the Registration Certificate or Seller’s Permit
The fastest place to look is the original registration document the state mailed when you applied. Depending on where you registered, it goes by different names: a seller’s permit, a certificate of authority, a certificate of registration, or a retail sales tax license. Whatever it’s called, the sales tax identification number is printed near the top.
Most states require you to display this certificate somewhere visible at your place of business, so it may already be hanging near the register or the front entrance. If you’ve moved since you registered, check old files and storage boxes. Losing the paper document doesn’t cancel your registration, and most state agencies will send a replacement through their online portal. The number itself doesn’t change because the paperwork went missing.
The same number appears on any resale certificates you’ve issued. When you buy inventory from a supplier without paying sales tax, the resale certificate you hand them carries your sales tax number. If copies are in your purchasing files, the number is right there.
Look at Past Sales Tax Returns
Every sales tax return you’ve filed shows your account number, usually at the top of the form. If you file electronically, the number is also in the confirmation email or receipt the state sent after each submission. Search your inbox for messages from your state’s department of revenue. The subject line typically references the filing period, and the body carries the account number.
Paper filers can pull physical copies. If an accountant or bookkeeper handles your filings, they have the number in their records. So does your accounting software. If you’ve set up sales tax collection in a platform like QuickBooks or Xero, the number is stored in the tax settings, and that’s often the quickest place to find it.
How much you have to sift through depends on your filing frequency. States assign businesses to monthly, quarterly, or annual schedules based on how much tax they collect. Annual filers have fewer returns to search; monthly filers will see the number repeated across dozens of documents.
Log Into Your State’s Online Tax Portal
Nearly every state revenue department has an online account portal where registered businesses can view their tax information. If you set up an account when you registered, log back in and look for a section labeled Account Summary, Registration Details, or Manage My Account. The sales tax number will be on the dashboard.
If you never set up online access, most portals let you create an account and link it to your existing registration using your business name, EIN, and business address. Some states also run a separate public-facing lookup tool where anyone can verify whether a business holds an active sales tax permit. Those tools are meant more for customers and vendors than for owners retrieving their own information, but they work in a pinch when you can search by business name or EIN.
Once you find the number, save a screenshot or PDF. That gives you a backup that beats logging in again, and it works as informal proof of registration until a replacement certificate arrives.
Call the State Tax Agency
When the digital options fail, the phone is the reliable fallback. Every state revenue department has a customer service line, and an agent can look up your account and read the number to you. You’ll need to verify your identity, so have your EIN or Social Security Number, your business name, and your business address ready before you dial.
Wait times vary. Early on a weekday, outside of filing-deadline weeks, is generally the shortest hold. While you have someone on the line, ask them to confirm your filing status and flag any outstanding obligations. Some states will mail a replacement certificate during the same call.
What You’ll Need for Any Lookup
Whether you’re using a portal, calling, or filling out a request form, you’ll usually need at least two of these to verify your identity:
- Your legal business name, exactly as registered, not a trade name or DBA unless that’s what’s on the registration.
- Your federal EIN, from your CP 575 notice, past federal returns, or the IRS.1Internal Revenue Service. Employer Identification Number
- Your business address or ZIP code, which narrows results if several businesses share a similar name.
- The owner’s Social Security Number, if you registered as a sole proprietor using an SSN instead of an EIN.
Pulling these together from your business formation documents before you start prevents the frustration of getting partway through a form and hitting a dead end because one field doesn’t match.
When the Number You Find Isn’t the Right Number Anymore
A sales tax number belongs to the specific business entity it was issued to. It doesn’t transfer with the business. If ownership has changed, the new owner needs a new registration and their own number. The same rule applies when a sole proprietor incorporates, forms an LLC, or otherwise changes the legal structure of the business. Operations can continue at the same address selling the same products, but the new entity needs its own permit.
Permit duration varies too. In some states, the permit stays active indefinitely as long as you keep operating and filing. In others, it expires after one, two, or five years and has to be renewed. Check with your state’s revenue department to find out whether yours has an expiration date, because letting it lapse means you’re collecting sales tax without authorization even though the number on your old certificate looks valid.