Every dollar you overpay in sales tax is a dollar not going back into your business. New York’s resale certificate, Form ST-120, lets you buy inventory tax-free at the wholesale level, keeping that money in play until your customer makes the final purchase and the obligation lands where it belongs.
But New York runs a tighter ship than most states. The wrong form, a missed deadline, or a certificate issued without proper registration can undo your exemption entirely, leaving you on the hook for back taxes, penalties, and interest. This guide covers what you need to know to use ST-120 correctly.
At Hands Off Sales Tax (HOST), we’ve been 100% focused on sales tax compliance since 1999. Whether you need help getting registered, reviewing your certificate practices, or defending against an audit, we handle it so you can stay focused on your business.
What Is Form ST-120?
Form ST-120 is New York’s official Resale Certificate, issued by the NYS Department of Taxation and Finance. Hand it to a supplier, and you’re certifying that what you’re buying will be resold and that you’ll collect and remit sales tax when the final sale happens.
It covers tangible personal property purchased for resale (in its present form or as a component of something you’ll sell), property used in performing taxable services where it becomes part of what’s delivered to the customer, and services purchased for resale.
Two things it won’t cover: motor fuel and anything you intend to consume yourself. If you buy tax-free under ST-120 and end up using the item in your own operations, use tax is immediately owed.
Contractors cannot use this form. They must use Form ST-120.1, the Contractor Exempt Purchase Certificate.
The Certificate of Authority: Get This First
Before you can use Form ST-120 as a registered New York vendor, you need a Certificate of Authority from the DTF. Think of it as New York’s sales tax license. It authorizes you to collect tax from customers and to issue and accept exemption certificates like ST-120.
A few things to know upfront:
- Apply through the New York Business Express portal. There’s no fee
- Apply at least 20 days before your first taxable sale
- Online applications process in roughly 5 business days; the certificate arrives by mail
- Valid for up to 3 years, renewable at the DTF’s discretion
The Certificate of Authority and ST-120 are different things. The Certificate lives in your place of business. The ST-120 is what you hand to suppliers. You need the first before the second means anything.
Does Form ST-120 Expire?
Technically, no. The form carries no expiration date. But it’s only valid while your Certificate of Authority is active. Let that lapse or get revoked, and your ST-120 certificates go with it.
In practice, many suppliers ask for a fresh ST-120 every few years as a precaution, even though New York doesn’t require periodic renewal of the certificate itself.
In-State vs. Out-of-State: Part 1 vs. Part 2
The form splits into two parts based on where you’re registered.
Part 1 is for registered New York State vendors. Enter your Certificate of Authority number, your business type, and what you’re buying for resale.
Part 2 is for out-of-state businesses that aren’t registered (and aren’t required to be) in New York. You can use ST-120 under Part 2 if goods are being delivered directly to your New York customers, or if they’re being resold from a location outside the state. Instead of a New York Certificate of Authority number, you provide your home state’s registration number. No home state number? Write “not applicable” and include your business location.
One rule applies universally: New York does not accept other states’ exemption certificates. A customer handing you their home state’s form instead of a completed ST-120 offers you zero protection.
A note for e-commerce sellers: if you store inventory in a New York fulfillment center, including Amazon FBA, you’ve established physical nexus regardless of your sales volume. That changes your registration obligations entirely. HOST’s nexus analysis service can help you identify exactly where those obligations begin.
Single-Use vs. Blanket Certificates
A single-use certificate covers one transaction. Done.
A blanket certificate covers all future purchases of the same general type from the same vendor. Submit it once, and it applies to every qualifying order going forward. Far more practical if you’re buying inventory from the same supplier regularly. One obligation most sellers miss: if your business address, Certificate of Authority number, or any other information on the blanket certificate changes, you must send an updated ST-120 to each affected supplier. Per the NYSDTF exemption certificate bulletin, an outdated blanket certificate creates audit exposure for both parties.
One catch: temporary vendors can only issue single-use certificates. Under New York law, a temporary vendor makes taxable sales in no more than two consecutive quarters in any 12-month period. If that’s you, blanket certificates aren’t an option.
If you don’t mark the blanket box on the form, the DTF defaults it to single-use.
The 90-Day Rule
You must deliver the completed ST-120 to the seller within 90 days of the purchase. Hand it over at the time of sale whenever possible. Miss that window, and both you and the seller can be held liable for the tax. Sellers are also within their rights to refuse your certificate even if it’s perfectly filled out, they’re not obligated to accept it. If that happens, pay the tax at the point of sale and then apply for a refund directly from the DTF using Form AU-11, Application for Credit or Refund of Sales or Use Tax.
One more note: New York accepts electronically issued certificates and digital signatures. A scanned PDF or email attachment is valid.
What Misuse Actually Costs You
New York takes fraudulent certificates seriously. Per the ST-120 form’s own certification language, misuse can result in:
- A $50 penalty per fraudulent certificate issued
- 100% of the tax that should have been paid on each misused transaction
- Criminal felony prosecution under New York State Law, punishable by a substantial fine and a possible jail sentence
- Revocation of your Certificate of Authority
The state backs this up with action. In 2024, Sotheby’s paid $6.25 million to settle charges tied to clients using resale certificates to dodge sales tax. The DTF doesn’t let these cases sit.
If you are accepting ST-120 certificates from customers, you carry risk too. New York can hold sellers liable for accepting invalid certificates even when done in good faith. That said, “good faith” has a specific meaning under NYSDTF’s own guidance: you’re protected if the certificate was received within 90 days, was properly completed, and you had no prior knowledge it was false or fraudulent. Protect yourself by verifying buyers through the NYS Registered Sales Tax Vendor Lookup tool before releasing an order. Confirm the status reads “Active.” An “Inactive” or “Suspended” result means the certificate is invalid, and the tax liability lands on you.
Record Retention and Audit Risk
Per NYSDTF’s recordkeeping requirements, you must keep all sales tax records including ST-120 certificates issued and received — for a minimum of three years from the return due date, or the filing date if later. New York’s standard audit window is three years under Tax Law §1147(b), extending to six years when taxable sales are underreported by more than 20%.
HOST recommends holding onto everything for at least four years as a buffer.
Mistakes That Will Cost You
Buying personal use items under ST-120.
This certificate is for resale, period. Use the items yourself, and you owe use tax immediately.
Issuing a blanket certificate as a temporary vendor.
If your sales pattern puts you in temporary vendor territory, single-use only.
Letting your Certificate of Authority lapse.
Your ST-120 is only as good as the Certificate behind it. An expired or revoked Certificate voids your exemptions retroactively.
Forgetting to update a blanket certificate.
Address change, new Certificate of Authority number, business name update, any of these requires a fresh ST-120 to every supplier who holds your blanket certificate. Stale certificates are a common audit target.
Accepting a customer’s out-of-state certificate.
It offers no protection in New York. Every customer claiming a resale exemption needs to complete ST-120 directly.
Blowing the 90-day deadline.
Late certificates expose both parties to liability.
How HOST Can Help
Sales tax compliance in New York comes with real consequences for getting it wrong. HOST has been exclusively focused on sales tax since 1999, and we’ve seen what happens when the details slip.
We handle nexus analysis and registration to make sure your Certificate of Authority is in place before you collect a dollar. We manage ongoing filings across every state you’re required to file in. And when the DTF comes knocking, our audit defense team steps in to organize documentation and represent your position.
If you have questions about your certificate practices or just want someone to make sure the details are right, reach out to HOST. You handle the sales — we handle the tax.
Frequently Asked Questions
Does Form ST-120 expire?
The certificate itself has no expiration date, but it’s only valid while your Certificate of Authority remains active. The Certificate of Authority is valid for up to three years and renewed at the DTF’s discretion. Let it lapse, and ST-120 goes with it.
Can an out-of-state business use Form ST-120?
Yes. Out-of-state buyers who aren’t registered in New York complete Part 2 of the form using their home state registration number. No New York Certificate of Authority needed, provided they’re not otherwise required to register here.
Can I use my home state’s resale certificate in New York?
No. New York doesn’t accept other states’ exemption certificates. Every buyer claiming a resale exemption in New York must complete ST-120 directly.
What’s the difference between a single-use and blanket certificate?
Single-use covers one transaction. Blanket covers all future purchases of the same type from the same vendor. Temporary vendors are limited to single-use. See the ST-120 instructions for the exact language.
What happens if I use ST-120 fraudulently?
Per the form’s own certification: a $50 fine per fraudulent certificate, 100% of the tax owed, criminal felony prosecution under New York State Law, and possible revocation of your Certificate of Authority. If you’ve received a notice or think your certificates are at risk, HOST’s audit defense team can help.
How long should I keep copies of ST-120 certificates?
NYSDTF requires a minimum of three years from the return due date or filing date. HOST recommends four years given New York’s six-year audit window for underreporting above 20%.
