Accounting Office / Accounts Payable

Iowa State University seeks to pay invoices promptly. If you have an inquiry about an unpaid invoice, please contact Carole Gill at 515-294-5181 or Please provide us with a purchase order number, invoice number and an amount when contacting us.

Common Reasons Why Invoices Have not been Paid:

  • The invoice was not mailed to Iowa State University, Accounts Payable, 3617 Administrative Services Building, Ames, IA 50011-3617.

    Please mail future invoices to this address, and fax any past due invoices to Carole Gill at 515-294-6470 or e-mail them to If you send the invoice to the department buying the materials, the Accounting Office will be unaware of the invoice unless the department forwards it to us.

  • The invoice was mailed to the correct address, but did not have a valid purchase order number.

    Before accepting an order, always get a purchase order number from the Iowa State University employee placing the order. If you have a valid purchase order number but do not put it on your invoice, your payment will be delayed while we attempt to determine the number. If you have a past-due invoice but do not have a valid purchase order number, contact the Iowa State University employee who placed the order and request that he or she provide you with a purchase order number. You will need to mail, e-mail, or fax a copy of the invoice, with the purchase order number included, to the Accounts Payable Office (see above) before payment can be made.

  • The department purchasing the materials has not approved the payment.

    Most payments under $5,000 do not require a positive approval. Instead, the department is sent an electronic document that will be paid in seven calendar days unless they choose to withhold payment. Payments for $5,000 or more do require a positive approval.

  • The department is disputing the charge due to incomplete delivery, damaged goods, malfunctioning equipment, etc.

    The Accounting Office cannot approve invoices for payment if the buying department disputes the charge. Please contact the Iowa State University employee who purchased the materials. After the dispute is resolved, the employee can approve the voucher for payment.

  • A W-9 Form was mailed to the vendor, but was not returned to Iowa State University.

    The IRS requires all payments for services to be reported as taxable income. This requires us to request a Taxpayer Identification Number before making payment. If we do not already have a W-9 Form on file for you, your payment will be delayed until we receive one. Although corporations sometimes are exempt from reporting, we require a Form W-9 to recognize the corporation status.

  • Iowa State University shows the check has been mailed, but the vendor has not received it.

    If the vendor has not received the check within ten business days after the check was issued, Iowa State University can put a "stop payment" on the original check and issue a replacement without charge. Please contact Carole Gill at 515-294-5181.

  • This page was last Updated on August 16, 2016.

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