How to verify a New York resale certificate (ST-120)

The short version. A New York resale certificate is Form ST-120, and it protects you when it is properly completed, in your hands within 90 days, and accepted in good faith. The state's Registered Sales Tax Vendor Lookup tells you whether the buyer's number belongs to a registered vendor. It does not check the certificate. Form ST-120 (1/26), the January 2026 revision, checked against the Department of Taxation and Finance's own PDF on September 25, 2026. Dates to keep: the completed certificate within 90 days of delivery, and three years from the due date of the return it relates to.

In January 2026 New York revised its resale certificate, and it did so quietly. We could find no note from the Tax Department on what changed, and most guides still describe the old form, including its label for the one number you most need to check. The rules for accepting the certificate did not change. The words on it did. If your checklist was written from an older guide, one line of it no longer matches the document in your hand. This page covers both: how to verify an ST-120, and exactly what the 1/26 revision changed. (New to this? How to verify a resale certificate covers the general shape of the job. For a state with no mandatory form at all, see California.)

What counts as a valid ST-120

The form's instructions to the seller state the whole test in one place. The certificate "will be considered valid if it was" accepted in good faith, "in the vendor's possession within 90 days of the transaction," and "properly completed (all required entries were made)."

"Properly completed" has a list behind it. New York's Tax Bulletin ST-240, Exemption Certificates for Sales Tax, says a certificate "must include all the following":

• the date it was prepared
• the purchaser's name and address
• the seller's name and address
• the identification number on the purchaser's Certificate of Authority
• the purchaser's signature, or an authorized representative's signature
• any other information required by that particular certificate

The last item points back at the form, and Form ST-120 is plain about what it wants: "Enter all the information requested on the front of this form." In practice that means the line describing the buyer's business ("I am engaged in the business of … and principally sell …"), Part 1 or Part 2 completed with at least one purchase box ticked, and the name and title of the person signing.

One difference is worth knowing if you sell into more than one state. New Jersey's instructions say the seller's name and address are not required on its certificate. New York's bulletin lists them. A New York certificate with your own details left blank is one to send back for completion, and the cure rule below gives you room to do it.

Blanket or single-use. The buyer marks one box at the top. If neither is marked, nothing is broken: "If you do not mark an X in the Blanket certificate box, the certificate will be deemed a Single-use certificate." What it costs you is coverage. An unmarked certificate covers one sale, not the account. Temporary vendors, who make taxable sales "in no more than two consecutive quarters in any 12-month period," "may not issue a blanket certificate."

What it cannot buy. Contractors cannot use the ST-120 at all; the form sends them to Form ST-120.1, a Direct Payment Permit (Form AU-297), or paying the tax. The certificate "does not exempt prepaid sales tax on cigarettes," it "may not be used to purchase motor fuel or diesel motor fuel," and it cannot cover anything the buyer is not reselling.

Most sellers need a Certificate of Authority too. The bulletin: "Most sellers must have a valid Certificate of Authority in order to accept an exemption certificate."

Part 1 or Part 2

The front of the ST-120 splits in two, and the split decides what you check next.

Part 1 is for registered New York vendors. The buyer certifies they are "a New York State vendor (including a hotel or short-term rental unit operator or a dues or admissions recipient), show vendor or entertainment vendor," or "a New York State temporary vendor," and writes their sales tax identification number. A temporary vendor also gives the date it expires. Then at least one purchase box:

• A. tangible personal property (other than motor fuel) bought for resale, or for use in performing a taxable service where it becomes part of the property serviced or passes to the customer
• B. "a service for resale, including the servicing of tangible personal property held for sale"
• C. "restaurant-type food, heated food, or heated drink for resale"

Part 2 is for buyers outside New York's system. The buyer certifies: "I certify that I am not registered nor am I required to be registered as a New York State sales tax vendor." They name the state or country where they are "registered to collect sales tax or value added tax (VAT)" and give that registration number. If their home jurisdiction issues none, they "indicate the location of your business and write not applicable" on the number line. Part 2 allows only two kinds of purchase:

• D. property for resale that "is being delivered directly by the seller to my customer or to an unaffiliated fulfillment services provider in New York State"
• E. "tangible personal property for resale that will be resold from a business located outside New York State"

The instructions add a detail to D that settles a common argument: "delivered by the seller includes delivery in the seller's own vehicle or by common carrier, regardless of who arranges for the transportation."

Two things follow for you as the seller. First, a Part 2 buyer has, by their own certification, no New York registration. The state's vendor lookup has nothing to find, and the number to look at is the one from their home jurisdiction. Second, Part 2 is a statement that the buyer is not required to register here. The previous revision of the form spelled out the plainest case against that: a purchaser with "any place of business or salespeople in New York State" is required to register. A Part 2 certificate showing a New York business address is worth a question before you accept it. That is what the "reasonable ordinary due care" half of the good-faith test is for.

The number, and its three names

The number in Part 1 has had several labels, and the guides have not caught up.

• The 1/26 form: "My valid sales tax identification number is"
• The 6/18 form it replaced: "My valid Certificate of Authority number is"
• Tax Bulletin ST-240: "the identification number on the purchaser's Certificate of Authority"

It is one number. The bulletin's phrase is the bridge: the sales tax identification number is the number printed on the buyer's Certificate of Authority, the document New York issues when a business registers.

What that number is, New York tells you on its registration page. It lists what will appear on a Certificate of Authority: the legal name, any DBA or trade name, the physical address of the selling location, and the "federal employer identification number (EIN) or, if you do not have one, a temporary New York ID number assigned by the Tax Department." So for a buyer with an EIN, the number on the ST-120 is normally that EIN: nine digits, usually written 12-3456789.

That makes New York different from states with their own numbering. In New Jersey, a nine-digit number where the state's twelve-digit ID belongs is a warning sign. In New York it is normal. What a nine-digit number cannot tell you is whether it belongs to a registered vendor. That is the lookup's job, and it is also why an EIN on its own is not a resale certificate.

The vendor lookup: what it proves

New York runs one public tool for this: the Registered Sales Tax Vendor Lookup. It opens with a security check, then takes the buyer's sales tax identification number. A match comes back as "Active Sales Tax Vendor Information": the number, the legal name, any trade name, and the sales tax address, with an option to print the page "for your records."

What that proves: the number belongs to a vendor registered with New York, and you can see whether the name on the certificate is the name the state has on file. Compare them.

What it does not prove: that the certificate is properly completed, that the person who signed it could sign for the business, or that this purchase is for resale. It also says nothing about a Part 2 buyer, who by definition is not registered here.

Print or save the result and keep it with the certificate. It is good evidence of the due care the good-faith test asks for. If the lookup finds nothing, that is a reason to ask the buyer, not proof of fraud. The number may have been copied wrong, and a buyer who belongs in Part 2 will not be there at all.

Our validator does not run this lookup for you. It sits behind a security check, so that step is yours.

Ninety days, good faith, and the cure rule

Ninety days, and when the clock starts. The form: "You must get a properly completed exemption certificate from your customer no later than 90 days after the delivery of the property or the performance of the service." The bulletin counts from the sale instead: "A purchaser must give the seller the properly completed certificate within 90 days of the time the sale is made, but preferably at the time of the sale." Take the certificate at the time of the sale, as the bulletin prefers, and the difference never matters.

After 90 days, the certificate alone no longer protects you. "When you receive a certificate after the 90 days, both you and the purchaser are subject to the burden of proving that the sale was exempt, and additional documentation may be required." A late certificate is no longer the protection the form describes. At best it is one piece of the proof, and the rest is up to you.

Good faith has two halves. The form: "A certificate is accepted in good faith when a seller has no knowledge that the exemption certificate is false or is fraudulently given, and reasonable ordinary due care is exercised in the acceptance of the certificate." Most guides quote only the first half. The bulletin puts the second half plainly: "You must exercise ordinary care when accepting a certificate." Due care is where checking comes in. The purchase fits the stated business, the Part fits the buyer, and the lookup finds the number.

On time but incomplete can be fixed. "An exemption certificate received on time that is not properly completed will be considered satisfactory if the deficiency is corrected within a reasonable period." A missing address or an unticked purchase box is a request to the buyer, not a lost exemption, as long as the certificate arrived on time and the gap is fixed within a reasonable period.

Tie the certificate to the invoices. "You must also maintain a method of associating an invoice (or other source document) for an exempt sale made to a customer with the exemption certificate you have on file from that customer."

The burden sits with you. "Sales transactions which are not supported by valid exemption certificates are deemed to be taxable retail sales. The burden of proof that the tax was not required to be collected is upon the seller."

Three years from the return, not the sale

The form: "You must keep this certificate for at least three years after the due date of the return to which it relates, or the date the return was filed, if later." The bulletin names the return more precisely: "at least three years from the due date of the sales tax return on which the last sale using the exemption certificate was reported."

Two things follow. The clock starts at a return, not at the sale or the signature, so it runs longer than "three years after the purchase date," the version some guides give. And for a blanket certificate, the clock does not start until the return that reports the last sale made under it, however long ago the buyer signed.

Blanket certificates do not expire, but they can go stale. From the bulletin: "If your address, identification number, or any other information on the blanket certificate changes, you must give your seller an updated blanket certificate. Your seller has the right to ask you for an updated blanket certificate at any time. Otherwise, the blanket certificate remains in effect as long as you are making exempt purchases from your seller."

Other states' certificates and the multi-state form

The bulletin is blunt: "Exemption certificates of other states or countries are not valid to claim exemption from New York State and local sales and use tax."

Neither multi-state form gets around that. New York is not among the states listed on the Multistate Tax Commission's Uniform Sales & Use Tax Resale Certificate, and it is not a member of the Streamlined Sales Tax agreement. A distributor who hands you an MTC form for a New York sale has handed you a form New York does not recognize. Wrong form for the state is one of the most common ways a certificate fails. The fix is an ST-120: Part 1 if they are registered in New York, Part 2 if they are not. (States split on this. New Jersey accepts the MTC form for resale; Louisiana does not.)

The 1/26 revision: what changed

We compared the 1/26 form line by line with the 6/18 revision it replaced. These are the changes of substance. Left out: typography, such as the purchase boxes now starting in lowercase and lettered lists turned into bullets.

Where	ST-120 (6/18)	ST-120 (1/26)
Part 1, vendor line	"including a hotel operator or a dues or admissions recipient"	"including a hotel or short-term rental unit operator or a dues or admissions recipient"
Part 1, both number lines	"My valid Certificate of Authority number is"	"My valid sales tax identification number is"
Signature block, name box	"Type or print name and title of owner, partner, or authorized person of purchaser"	"Name and title of owner, partner, or authorized person of purchaser (Type or print)"
Purchaser information heading	"Purchaser information – please type or print"	"Purchaser information"
Page 2, top	A "New" note: from June 1, 2018, use box C for restaurant-type food or drink bought for resale, with a pointer to memo TSB-M-18(1)S	Removed. Box C itself is unchanged.
Page 2, registration	Several paragraphs on when an out-of-state business must register: a place of business or salespeople in the state, residents paid for referring customers, related businesses in New York. Three earlier Tax Department memos cited, and a line to contact the department for help	One paragraph: "A business that has no physical presence in New York State but meets certain criteria must be registered as a New York State vendor." It adds that such a business must register "immediately" and points to the Tax Department's website
Page 2, misuse penalties	The revocation penalty pointed to memo TSB-M-09(17)S	The pointer is gone. The penalty is unchanged.
Page 2, Part 2 delivery note	A separate "Note:"	Folded into the sentence it explains, same meaning

Two changes carry real content. The short-term rental words follow a new tax. New York's sales tax return instructions (Form ST-100-I) put it this way: "Effective for collections of rent by an operator or booking service on and after March 1, 2025, New York State and local sales tax is imposed on sales of short-term rental unit occupancy in this state." And the registration paragraph now states the general rule for businesses with no physical presence in New York, in place of a list of specific triggers. The rest is wording and housekeeping.

What did not change: the 90 days, the good-faith test, the cure rule, three-year retention, the misuse penalties, single-use and blanket certificates, the temporary-vendor rules, and the limits on contractors, cigarettes and motor fuel.

Certificates on the 6/18 form will be in your files for years, because a blanket certificate stays in effect while the buyer keeps buying. We have found nothing from the Tax Department saying a certificate on the older form stops working, and the rules it is judged by are the same. If your checklist or intake form asks for the "Certificate of Authority number," it still points at the right number. On a 1/26 certificate, that number sits on the line labeled "sales tax identification number."

Where guides get it wrong

The number's label changed. The 1/26 form asks for a "sales tax identification number." Guides that tell buyers to write their "Certificate of Authority number" describe the old form. The number is the same.

Retention runs from a return, not a purchase. "Three years after the purchase date" is shorter than the state's rule, which starts at the due date of the return, or the filing date if later.

Nothing we found puts a three-year limit on a Certificate of Authority. Not the form, and not the Tax Department's bulletins on exemption certificates and registration. The form asks for an expiry date only from a temporary vendor. A regular Certificate of Authority can still be suspended or revoked, which is one reason to run the lookup.

The checklist version

• Right form: an ST-120, not another state's certificate or the MTC form, and not an ST-120.1 (contractors)
• Every entry on the front: seller and purchaser names and addresses, the business line, date prepared, the signer's name and title, and the signature
• Part 1 or Part 2 completed, with at least one purchase box ticked
• Part 1: a sales tax identification number (usually the buyer's nine-digit EIN), run through the Registered Sales Tax Vendor Lookup, with the result saved
• Temporary vendor? The expiry date is filled in, and the certificate is single-use
• Part 2: the buyer's home state or country and its registration number (or "not applicable" with a location), and box D or E fits how the goods move
• Blanket box marked if it should cover repeat purchases. Unmarked means single-use.
• In your hands within 90 days of delivery or performance
• Invoices tied back to the certificate on file
• Kept three years from the due date of the return it relates to, or the filing date if later. For a blanket, count from the return that reports the last sale under it.

Or skip the manual pass: our free validator reads New York resale certificates (ST-120, both the 1/26 and the 6/18 revisions), checks the required fields, whether Part 1 or Part 2 is filled in with a purchase box ticked, and the temporary-vendor rules. You see whether it passes, and how many issues it has, with no signup. Add your work email to see each finding with the rule behind it and download a timestamped PDF of the result. It does not run the state's vendor lookup; that step is yours. Hello Sales checks a resale certificate against the state's own rules and tells you which field fails and why. Run yours through →

New York is a records problem as much as a document problem: three years counted from a return rather than a date on the certificate, blanket certificates that must be replaced when the buyer's details change, and nothing that tells you when a buyer's registration lapses. The free validator checks one certificate at a time. Keeping them all on file — the document, the values read from it and the result of each check, with an audit trail — is what the paid product is for.

Questions people ask

How do I verify a New York resale certificate?

Check the ST-120 against the state's three-part test: properly completed, in your hands within 90 days, and accepted in good faith. Properly completed means the date, both parties' names and addresses, the buyer's number, the signature, and everything else the form asks for, including a purchase box in Part 1 or Part 2. Then run a Part 1 buyer's sales tax identification number through the Registered Sales Tax Vendor Lookup and save the result with the certificate.

What changed on the ST-120 in January 2026?

The number line now reads "sales tax identification number" instead of "Certificate of Authority number." The Part 1 vendor line adds short-term rental unit operators. The signer's name box is relabeled, and page 2 drops a 2018 note and several older references on who must register. The rules for accepting the certificate did not change: 90 days, good faith, the cure rule and three years all read as before.

Is the sales tax identification number the same as the Certificate of Authority number?

Yes. It is the number on the buyer's Certificate of Authority, which the 1/26 form simply calls by another name. For a business with an EIN, it is normally the EIN. A business without one gets a temporary New York ID assigned by the Tax Department.

Does a New York resale certificate expire?

The form carries no expiration date. A blanket certificate "remains in effect as long as you are making exempt purchases from your seller," but the buyer must give you an updated one if their address, number or other details change, and you can ask for a fresh one at any time. A temporary vendor's number carries its own expiry date on the form.

Can an out-of-state buyer use the ST-120?

Yes. An out-of-state buyer registered in New York uses Part 1, like any New York vendor. One who is not registered and not required to be uses Part 2. They give their home state or country and its registration number, or "not applicable" with their location. The purchase must either be delivered by you to their customer or to an unaffiliated fulfillment provider in New York, or be resold from a business outside New York. Other states' certificates and the MTC multi-state form are not valid for New York sales.

What happens if the certificate arrives after 90 days?

It no longer protects you on its own. Both you and the buyer carry "the burden of proving that the sale was exempt, and additional documentation may be required." A certificate that arrives on time but incomplete is different: it counts if the gap is fixed "within a reasonable period."

How long do I keep a New York resale certificate?

At least three years after the due date of the return it relates to, or the date that return was filed, if later. For a blanket certificate, count from the return that reports the last sale made under it.

What are the penalties for misusing an ST-120?

For a buyer who misuses one, the form lists "A penalty equal to 100% of the tax due," "A $50 penalty for each fraudulent exemption certificate issued," criminal felony prosecution, and revocation of the Certificate of Authority. For the seller, the risk is being held liable for the tax that was not collected on any sale not backed by a valid certificate.

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Form ST-120 (1/26), checked against the Department of Taxation and Finance's PDF on September 25, 2026, and compared line by line with ST-120 (6/18). Rules cited from the form's instructions and from Tax Bulletin ST-240 (updated January 21, 2026).

(General education, not tax advice — the New York State Department of Taxation and Finance or a SALT professional is the authority for your situation.)