Northwestern Tax Exempt Form: Illinois Use, Limits, and Penalties

To use Northwestern University’s tax-exempt status on a purchase, you don’t download a Northwestern tax exempt form yourself. Procurement and Payment Services controls the university’s Illinois exemption certificate and provides it three ways: through the standard Northwestern purchase order, through a pre-approved one-time use letter for employees or student groups, or by sending the official certificate directly to a vendor that won’t accept the first two.¹ The exemption itself rests on Northwestern’s Illinois sales tax exemption identification number (its E-number), issued to the university as a 501(c)(3) educational institution.²

How to Get the Form

Northwestern does not distribute copies of its official Illinois tax-exempt certificate to individual departments, schools, or students. The certificate lives with Procurement and Payment Services, and the office sends it to vendors when needed.¹ You cannot simply print it and hand it to a store clerk.

There are three routes, and the right one depends on how you’re buying:

The Northwestern purchase order. The standard PO already references the university’s tax-exempt status in its terms. For most routine vendor relationships, that reference is enough and no separate certificate is needed.
A one-time use letter. Faculty, staff, and student groups can use a pre-approved letter for an individual purchase. Separate versions exist for employees and for student organizations, and both are available through the Procurement and Payment Services website.
The official certificate, sent by Procurement. If a vendor will not accept a purchase order or a one-time letter, Procurement and Payment Services sends the official Illinois tax-exempt certificate directly to the vendor on the university’s behalf.

For access to the one-time use letters or any question about a specific vendor, contact the procurement office at procurement@northwestern.edu.¹

Which Illinois Form Actually Applies

The Illinois form used to document a tax-exempt purchase is Form CRT-61, the Certificate of Resale, which also covers exemption claims.³ It is sometimes confused with Form ST-1, which is a different document entirely: the ST-1 is the sales and use tax return that retailers file with the state, not a buyer’s exemption certificate. Using the wrong form number with a vendor will slow the transaction down or get the exemption rejected.

The CRT-61 can be completed as a blanket certificate covering all future qualifying purchases from a specific vendor, or as a single-purchase certificate for one transaction. It asks for the purchaser’s name, address, E-number, a description of what is being bought, and a signature certifying that the purchase qualifies. Certificates of resale and exemption should be updated at least every three years.³ Buyers can also create their own certificate in place of the state-printed form as long as it contains the required information, which is the role Northwestern’s one-time use letters play.

Information You’ll Need on the Certificate

Whether you’re filling out a CRT-61, a one-time use letter, or any equivalent document, a few pieces of identifying information have to appear:

The Illinois E-number issued to Northwestern by the Illinois Department of Revenue. This is what vendors use to verify the exemption.⁴
Northwestern’s Federal Employer Identification Number: 36-2167817.⁵
The university’s full legal name and Evanston campus address.
A clear description of what is being purchased. “Supplies” is not enough; something like “laboratory glassware for chemistry department” or “office furniture for Kellogg School of Management” ties the goods to university operations and holds up better if a vendor or auditor questions it.
The signature of an authorized person, typically a procurement officer or someone in financial operations designated to certify purchases. That signature is a legal declaration that the purchase qualifies.

The basis for the exemption is that Northwestern is an educational organization holding an active exemption identification number, which is what Illinois law requires for a nonprofit purchase to be exempt from sales tax. If a vendor asks for a copy of Northwestern’s IRS determination letter confirming its 501(c)(3) status, that can be requested through Tax and Regulatory Services in the Controller’s Office.²

Using the Certificate at Checkout

For in-store purchases, give the vendor a physical copy of the one-time use letter or completed CRT-61 before checkout. Most Illinois retailers recognize E-numbers and can verify the exemption through the Department of Revenue’s system. For online orders, vendors typically have a tax-exemption portal where you upload the documentation before completing the purchase. Some national retailers, including Amazon and Staples, run dedicated tax-exempt account programs that keep the certificate on file so it applies automatically.

Always check the final invoice or receipt to confirm the sales tax was actually removed. Catching a mistake at the register is much easier than chasing a refund later. If a vendor refuses the certificate or asks for something more, don’t try to resolve it on your own. Contact Procurement and Payment Services; the office has the official certificate and the authority to send it directly to the vendor.¹ The savings can matter: combined state and local sales tax in parts of Illinois tops 10%.⁶

Purchases Outside Illinois

The Illinois E-number only works for purchases within Illinois. Other states have their own exemption frameworks, and each requires separate registration. Northwestern has gone through the process in several states beyond Illinois, and Procurement and Payment Services keeps those certificates on file and provides the right one directly to the vendor.¹ In states where the university has not registered, the purchase will include sales tax unless a separate exemption can be obtained. Some states accept the IRS determination letter as sufficient proof of nonprofit status; others require their own application. Procurement can advise on whether a given state is covered.

What the Exemption Does Not Cover

The exemption applies to purchases of tangible personal property for university use. It does not apply to personal purchases by employees, students, or anyone else, even at a tax-exempt institution. A personal laptop or your own groceries cannot be bought under Northwestern’s E-number.

Prepared meals are a frequent point of confusion. Food purchased from restaurants or prepared for immediate consumption is generally taxable in Illinois regardless of who’s buying it. Hotel occupancy taxes fall under a separate framework and are not covered by the standard sales tax E-number either.

Penalties for Misuse

Illinois treats misuse of an exemption number as a serious matter. Under the Retailers’ Occupation Tax Act, obtaining a registration or exemption number through misrepresentation, falsely claiming to hold one, or using a valid number for purchases that do not qualify is a Class 4 felony, which carries potential prison time. That applies to individuals who fabricate an exemption and to authorized university personnel who use the E-number for purchases outside legitimate institutional purposes. Vendors are cautious for the same reason: if an exemption certificate is improperly issued and the Department of Revenue later audits the transaction, the vendor can be left on the hook for the uncollected tax, which is why some ask for additional verification before removing sales tax at the register.

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Northwestern University. Tax Exempt Status – Procurement and Payment Services
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Northwestern University. Tax Exempt Status
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Illinois Department of Revenue. Certificate of Resale
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Illinois Department of Revenue. Sales and Property Tax Exemptions
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Northwestern University. Ways to Give
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Illinois Department of Revenue. Sales Tax Rate Change Summary, Effective January 1, 2026