United States · New York · Tax Department
New York resale certificate ST-120 and the 90-day rule.
Look up whether a buyer is an active registered vendor, then test whether their ST-120 arrived inside the 90 days that protect you if you are audited.
ST-120 acceptance window
This is a format and date check only. It cannot tell you a number is active. Only the official verifier can.
Result
Enter the delivery date and, if you have it, the date you received the ST-120.
Verify a New York sales tax vendor
New York calls its registration a Certificate of Authority. The Tax Department's "Look Up a Sales Tax Vendor" service is described as a way to verify that a business that gave you an exemption certificate is an active, registered sales tax vendor. The Tax Department links it from its sales tax page as the Registered Sales Tax Vendor Lookup. Registration matters because only a registered vendor can legally issue or accept most New York exemption certificates, and Form ST-120 Part 1 asks the buyer for its valid sales tax identification number. TNAADO could not find a published layout for that number, so this page does not decode it.
What a result means
- Active registered vendor: the buyer can complete Part 1 of the ST-120 and you can accept it.
- Not active or not found: a buyer who is not registered may still use Part 2 if they are registered in another state or are not required to be registered, but they must state their home jurisdiction and registration number. Otherwise treat the sale as taxable.
- Selling without a valid Certificate of Authority carries penalties: up to $500 for the first day and up to $200 for each later day, capped at $10,000 (Publication 750, 11/15 edition).
The ST-120 and its 90-day clock
The current ST-120 (revised 1/26) comes as a single-use or a blanket certificate. Its instructions say a seller is protected from liability for the tax if the certificate was accepted in good faith, was in the vendor's possession within 90 days of the transaction, and was properly completed. Good faith means you had no knowledge it was false and used reasonable ordinary care. If you receive the certificate after the 90 days, both you and the buyer share the burden of proving the sale was exempt and extra documentation may be needed. A certificate received on time but incompletely filled in is treated as satisfactory if the gap is fixed within a reasonable time. You must also be able to link each exempt invoice to the certificate on file.
Misuse penalties for the buyer
The form lists a penalty equal to 100% of the tax due, $50 for each fraudulent exemption certificate, possible felony prosecution, and revocation of the Certificate of Authority. A buyer who buys for resale but then uses the goods must report and pay the tax directly to New York.
Do you need a Certificate of Authority to sell on Etsy?
The Tax Department's marketplace guidance addresses a home-based seller who sells only through a marketplace provider that collects tax. Its answer: "You still need to apply for a Certificate of Authority to be a sales tax vendor", and the sales go on your return in gross sales and nontaxable sales. The provider must give you Form ST-150 within 90 days of the sales it facilitates, or publish an agreement saying it collects. Apply at least 20 days before you start business, and display the certificate at your place of business.
Worked example
Goods are delivered on 1 January 2026. Day 90 is 1 April 2026, so an ST-120 received on 1 April is in time and one received on 2 April is not. The calculator above counts the delivery date as day zero.
Sources
- Form ST-120, Resale Certificate (1/26) — 90-day validity, good faith, penalties, Part 1 and Part 2
- Tax Department sales tax page — link to the Registered Sales Tax Vendor Lookup
- NY.gov: Look Up a Sales Tax Vendor — describes the lookup as verifying an active, registered sales tax vendor
- Tax Department: sales tax requirements for marketplace providers — marketplace sellers and the ST-150
- Publication 750, A Guide to Sales Tax in New York State (11/15) — Certificate of Authority timing and penalties; older edition
All figures and rules above were retrieved October 2026. Agencies revise forms and thresholds, so confirm anything that affects a sale against the current official page.
Frequently asked questions
How long do I have to collect a New York ST-120?
The ST-120 instructions say the certificate must be in the vendor's possession within 90 days of the transaction for the seller to be protected.
What if I get an ST-120 after 90 days?
Both you and the purchaser share the burden of proving the sale was exempt, and more documentation may be required.
Can I sell on Etsy in New York without a Certificate of Authority?
The Tax Department says a home-based seller whose sales all go through a marketplace provider still needs to apply for a Certificate of Authority.
Where do I check whether a buyer is a registered vendor?
Use the Tax Department's Look Up a Sales Tax Vendor service, linked from tax.ny.gov.
Not legal or tax advice
This page explains published agency guidance and runs simple date and format checks. It is not a certificate, a legal opinion or confirmation that any permit is active. Verify with the state before relying on a customer's exemption.