How to Fill Out NJ ST-4 Exempt Use Certificate

To fill out New Jersey’s ST-4 Exempt Use Certificate, download the current form from the Division of Taxation, enter the seller’s and your business’s legal names and addresses, provide your 12-digit New Jersey Taxpayer Identification Number, check the statutory exemption that matches how you’ll actually use the purchase, describe the item specifically, mark whether it’s a single-purchase or blanket certificate, then sign and date it and hand it to the seller.¹ The seller keeps the form; it’s never sent to the state. Getting each field right is what stands between a clean tax-free purchase and a back-tax assessment four years later.

Before You Fill It Out

Confirm the purchase actually qualifies. The ST-4 covers items a taxable business will put to a specific exempt use, most commonly machinery used directly and primarily in manufacturing, or property used directly and exclusively in experimental or laboratory research.² If you’re buying goods to resell, that’s a different form, the ST-3. If your organization itself is a tax-exempt entity like a nonprofit, that’s the ST-5. Using the ST-4 for either of those situations is the wrong document.

You’ll also need your New Jersey Taxpayer Identification Number ready. It’s the 12-digit number assigned when you registered with the Division of Revenue and Enterprise Services, built from your federal EIN (or Social Security Number for sole proprietors) plus a three-digit suffix.³ An out-of-state business that isn’t registered in New Jersey may substitute its home-state tax ID or federal EIN.

What Goes on the Form

The current version of Form ST-4 is dated 11-24 and available as a PDF from the Division of Taxation.¹ You can also reproduce copies privately without the Division’s prior permission. The form is short, but each field carries weight.

Seller and Purchaser Information

Enter the seller’s full legal name and business address at the top. Below that, enter your own business’s legal name and address exactly as they appear on your tax registration. Mismatches between the name on the form and the name in the Division’s records are a common reason certificates get flagged. Add your 12-digit New Jersey Taxpayer Identification Number in the field provided.

Exemption Category

The form lists checkboxes for each statutory exemption. Check the one that fits the actual use of the purchase, not the one that sounds broadest. If you check manufacturing but the equipment is really for quality-control testing, an auditor will deny the exemption and assess back taxes with interest.

Description of the Property or Services

Describe what you’re buying in enough detail that an auditor can draw a clear line between the item and the exempt activity. “Machine parts” is too vague. “Replacement conveyor belt rollers for Widget Assembly Line 3” shows exactly how the purchase ties into production. Sellers who see vague descriptions often refuse the certificate rather than take on the tax risk themselves.

Blanket or Single-Purchase

Check whether the certificate covers a single transaction or all future qualifying purchases from the same seller.⁴ A blanket certificate stays valid as long as you maintain a recurring business relationship with that seller, defined as no more than 12 months passing between transactions.⁵ If that recurring relationship continues, the Division cannot require the seller to obtain a renewed blanket certificate. For regular exempt purchases from the same supplier, a blanket certificate saves you from filling out a fresh form every time.

Signature and Date

An authorized representative of the purchasing business must sign the form, and the signature acts as a sworn statement made under penalty of perjury. For paper or faxed certificates, a physical or facsimile signature is required.⁴ Add the date of execution so it’s clear when the exemption claim was made relative to the sale. A form without a signature is incomplete, and no seller should accept one.

What “Directly and Primarily” Means

The most common mistake with the ST-4 is treating any equipment used in a factory or lab as automatically exempt. The manufacturing statute requires the machinery to be used “directly and primarily” in production. A machine that shapes, cuts, or assembles your product qualifies. Office furniture, break room appliances, and warehouse lighting do not, even though your operation can’t function without them, because their connection to the actual production process is incidental.

The statute also excludes several categories outright: energy, motor vehicles, parts with a useful life of one year or less, and tools or supplies used with exempt machinery.⁶ You can claim the exemption on a new CNC milling machine but not on the electricity running it or the drill bits you replace every few months.

The research and development exemption works the same way, with an even stricter standard: “directly and exclusively” in experimental or laboratory research. Routine quality-control testing, efficiency surveys, management studies, consumer research, and advertising work do not qualify, even if your company files them under “R&D.”⁷

After You Sign It

Give the completed form to your seller. They keep it in their files as proof of why they didn’t collect tax; the form is never sent to the Division of Taxation.² Once accepted, the sales tax should come off your invoice.

A seller who accepts a properly completed certificate in good faith is relieved of liability for the tax, even if it later turns out you weren’t actually eligible.² Good faith has a specific meaning: the exemption must have been legally available on the date of the transaction, plausible for the item being purchased, and reasonable for your type of business.⁸ A restaurant handing over an ST-4 to buy a pizza oven under the manufacturing exemption should draw an obvious refusal. A seller who knowingly accepts a certificate with materially false information loses that protection.

If the seller doesn’t collect the certificate at the time of sale, they have 90 days after the sale to obtain it and still avoid liability.⁵ After that, the tax falls on the seller.

Recordkeeping and What Happens If You Get It Wrong

Both buyer and seller must keep copies of completed ST-4 certificates for at least four years.⁹ For a blanket certificate, the four-year clock runs from the date of the last sale it covered, not from when the form was signed.⁵ The Division can demand these records during an audit, and if you can’t produce them, expect an assessment.

A purchaser who claims an exemption they didn’t qualify for owes the full unpaid sales tax, plus interest and penalties.⁴ The state’s sales tax rate is 6.625 percent.¹⁰ For 2026, New Jersey charges 10 percent annual interest on outstanding tax balances, calculated as the prime rate plus 3 percent.¹¹ Because the certificate is signed under penalty of perjury, intentionally false claims carry more severe consequences than a good-faith error. If you’re not sure whether a purchase fits within an exemption, resolve that question before you sign, not four years later during an audit.

1
NJ.gov. ST-4 Exempt Use Certificate
2
NJ.gov. New Jersey Sales Tax Guide – Tax Topic Bulletin S and U-4
3
NJ.gov. Starting a Business in New Jersey – New Jersey Tax Guide
4
NJ.gov. Sales Tax Exemption Administration
5
LII / Legal Information Institute. NJ Admin Code 18-24-10.5 – Exemption Certificates; Conditions, Retention, and Inspection
6
Justia. New Jersey Revised Statutes Section 54-32B-8.13 – Sales, Use Tax Exempt, Machinery, Apparatus, Etc.
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Justia. New Jersey Revised Statutes Section 54-32B-8.14 – Sales of Tangible Personal Property, Specified Digital Products for Use in R and D Exempt; Exceptions
8
LII / Legal Information Institute. NJ Admin Code 18-24-10.4 – Acceptance of Exemption Certificates
9
LII / Legal Information Institute. NJ Admin Code 18-18A-7.1 – Record Retention
10
NJ.gov. NJ Division of Taxation – Sales Tax Transition
11
NJ.gov. Interest Rate Assessed on Tax Balances for 2026