Purchasing and Expense Reimbursements

Jump to a Section

Sales Tax

Tax exemption will be granted for purchases exclusively for use by Northwestern University. Purchases for personal use by individuals, faculty, staff, or students are not qualified for tax exemption. Since the University is exempt from paying Sales and Use tax, these taxes are generally not reimbursable when an employee has used personal funds for the purchase. A special exception may be requested from the employee’s dean or department head in cases where it can be clearly demonstrated that the purchase and payment of tax was unavoidable or an emergency. This should be rare. 

Requests for Northwestern's Tax-Exemption Certificate

Procurement and Payment Services (PPS) keeps information on file related to Northwestern’s tax-exempt status in Illinois and in several other states. If a department/school needs proof of Northwestern’s tax-exempt status, please adhere to the following: 

  • An official Purchase Order (PO) should be issued to vendors for University purchases. The document references the standard NU Purchasing terms which includes tax-exempt information. 
  • An Illinois Tax Exempt One-Time Use Letterfor use by Faculty and Staff and anIllinois Tax Exempt One-Time Use Letterfor use by Student Groups is available for individual purchases that many vendors will accept, which includes appropriate approval information. Please contact Jennifer Young if you need a signed tax-exemption letter.  
  • When using the One-Time Use Letter, the associated purchase must be made with an official form of payment from the University, such as the issuance of a formal PO or charging a Northwestern Corporate Card (P-Card).  If using a non-Northwestern form of payment (such as cash, personal check, or personal credit card), the transaction must be less than $400 and you must request a separate employee certification form from PPS that will to be provided to the merchant in addition to the One-Time Use letter.  To request a separate employee certification form, email the following information: vendor name, vendor address, detail of what will be purchased, estimated amount, and explanation of why an official form of Northwestern payment cannot be used.
  • PPS can send the official Illinois Tax-Exempt Certificate (or the official certificate from other states where NU is tax-exempt) directly to vendors that do not accept the above One-Time Use letter. PPS does not provide the official Illinois tax-exempt letter to departments/schools.
Back to top

Travel and Expense Reimbursements

  • Northwestern's Travel and Entertainment policy can be found on the PPS website. 
  • Students, research staff, and postdocs can use this online form to have a ChBE staff member submit the expense report on their behalf. 
  • Please see the Reimbursement Quick Guide for a concise breakdown of how to file for reimbursement.

What to include with your expense report:

  • The University’s reimbursement policy is based on documentation of reasonable and actual expenses supported by original itemized receipts. Original itemized receipts must be submitted for all travel expenses, including prepaid expenses such as flights booked through Egencia or purchases charged to the department p-card. Monthly credit card statements and/or travel agency invoices alone are not acceptable as backup documentation.  
  • Note: If the per diem reimbursement method is selected, then receipts are not required for meals and incidental expenses. Please consult the Per Diem section for details.


  • Airfare: E-ticket receipt including payment method and/or copy of confirmation from Egencia if applicable
  • Ground transportation: taxi, ride share, train, shuttles, parking, tolls, etc. 
  • Personal auto use: use an online mapping program to show the route taken and the mileage incurred. You will be reimbursed using the current IRS mileage rate which covers fuel, maintenance, insurance, transportation, and operating costs. Do not submit receipts for gas purchased during your trip - it is included in the mileage rate. 

Lodging: final bill with number of nights and amount paid and payment method (include Egencia confirmation if applicable). 

Conference registration: Registration receipt showing conference fee payment and the name and dates of conference. This also applies if the registration was prepaid using the department p-card.


  • Restaurants: Itemized receipt listing the items purchased 
  • Tips are reimbursable. Submit the receipt that includes the tip that was included with the bill. 
  • You have the option of using per diem (see below) instead of submitting receipts for individual meals.

Exceptions: If you are requesting to be reimbursed for travel more than 90 days after your return or for an expense that falls outside of the travel and entertainment policy guidelines, you will be required to complete the Reimbursement Exception & 90-Day Exception Form. (Please contact Jenna Jones for assistance.) 

Per Diem: An alternative to submitting receipts is the use of per diem. Per diem is a method of reimbursement for travel expenses that allows a set dollar amount per day. The maximum rate is determined by the government and varies by city. Northwestern University has instituted the use of per diem for M&IE (Meals and Incidental Expenses) only. Partial per diem is allowable. The first and last day of travel are charged at 75% of the daily rate. The per diem covers reimbursement for meals, snacks, tips and fees. 

Use of per diem must be established before the trip commences. If your travel expenses are being reimbursed from funding courtesy of your advisor or PI, you must obtain his or her authorization in advance. 

When submitting your expense report with per diem, print the table showing the rate for the city you visited from the GSA website. Include a PDF of the rates for the city where you traveled with your expense report. 

Commercial Rental Vehicles: The University's designated vehicle rental agency should be used whenever possible. You should always opt for a midsize, economy, compact or subcompact vehicle (visit Procurement's website for more information). Travelers should not purchase a collision damage waiver (CDW) from the rental agency if the rental is in the U.S or Canada; coverage should only be purchased for international rentals. Travelers must report all accidents to the Office of Risk Management within 24 hours, or immediately if the accident results in personal injury or towing of a vehicle. The traveler should follow the rental agency accident report instructions in addition to forwarding a copy of the report to the Office of Risk Management. 

Sales tax: Tax exemption is to be used exclusively to make purchases for use by Northwestern University. It will not be granted for purchases that are for personal use by individuals, faculty, staff, or students. Since the University is exempt from paying Sales and Use tax, these taxes are generally not reimbursable when an employee has extended personal funds for the purchase. A special exception may be requested from the employee’s dean or department head in cases where it can be clearly demonstrated that the purchase and payment of tax was unavoidable or an emergency. This should be rare. Additional information regarding tax exemption requests can be found on ChBE’s Resources Page.

Back to top

Purchasing Procedures

All purchases must be made by department staff. Students, faculty, and researchers are not authorized to order directly from vendors; you may request a purchase through iBuyNU or the Smartsheets purchase order form. See the ChBE purchasing instructions for requesters and approvers for further guidance on the Smartsheets purchase form process.

Remember to keep your preferred lab contact up to date! 

Catalog Orders (iBuy)

  • Graduate students, faculty, and staff are given access to iBuyNU, Northwestern's online shopping catalog, to purchase items for research or academic use. Requests to purchase items through iBuyNU are referred to as catalog requisitions. 
  • See the FFRA Training website for the iBuyNU Job Aid.  
  • Shoppers should assign iBuyNU carts to their lab’s designated administrator
  • Enter the chart string for the purchase as a comment in the cart. 

Non-Catalog Orders 

  • Purchases from a company whose catalog is not in iBuyNU are referred to as non-catalog requisitions. 
  • Shoppers must submit these orders using the Smartsheets purchase order form. Required information includes:
  • Name of the person requesting the order
  • Name of Chart-string approver (or note about why approval is not needed)
  • Supplier name
  • Order total ($) 
  • Chart-string
  • PDF file of the quote or cart associated with the order
  1. When the order is approved, an email will be sent to "ChBE Purchases." The staff member assigned to your order will then enter the requisition for your order.
  2. After the purchase order is dispatched, the purchase order number (beginning with PUR) will be added to the Smartsheet and you will receive a confirmation email with the purchase order number. This information is important to reference if you contact the supplier regarding your order. 
  3. Make sure to scroll to the bottom of the confirmation email in case the chart-string approver left any comments.
  4. You can view the status of your order, as well as read comments and reference the purchase order number, on the shared Smartsheet. 
  • Please review the ChBE purchasing instructions for requesters and approvers for further information.

Receiving Your Order 

  • When your order arrives, you will receive an email from a staff member. In some cases, you may receive a delivery notification from the vendor-this does not indicate the delivery has made its way to the department.  
  • Come to room E136 with your Wildcard and a ChBE staff member will scan your packages for pickup. 
  • If something is missing, please follow up with the vendor first. If an item needs to be canceled from an order, please inform your designated administrator

Additional Information  

  • If you would like to order a restricted item from Amazon via iBuyNU, please contact to submit a request for the restriction to be lifted.  
  • If the restriction on the item cannot be lifted, or if we are unable to reach a purchasing agreement with a supplier, we may have the option to use the department’s corporate card (p-card) for the purchase. The p-card is only to be used as a last resort for low-dollar-amount transactions. 
  • If you know that a purchase order has been dispatched for your order, but the item has yet to be delivered within a reasonable time frame, please follow up directly with the vendor and provide the purchase order number (starts with “PUR”). If the item has shipped, ask a ChBE staff member to search the package management database for tracking information on your order. 
  • If a company contacts you about late payment for an invoice, please alert a ChBE staff member immediately. Include the invoice and the purchase order number. 

Back to top