Do you mean UPS - the package delivery company with the brown trucks? Or do you mean USPS - the United States Postal Service (the "post office")? You can use either UPS or USPS to send your federal tax return to the IRS, but the address you have to send it to is different. The IRS refers to UPS as a "private delivery service."
What address did you have that they said was incomplete? What state are you in?
If you are using the U.S. Postal Service, the mailing address is in the filing instructions that TurboTax printed along with your tax return. Or go to the following link, then click the name of your state to find the address to mail your federal tax return to.
https://www.irs.gov/uac/where-to-file-paper-tax-returns-with-or-without-a-payment
If you are using UPS, first follow the instructions above to determine what city you would mail your federal tax return to if you were using the U.S. Postal Service and not enclosing a payment. Then go to the link below to find the corresponding address to use if you are sending your federal tax return by a private delivery service.
https://www.irs.gov/uac/submission-processing-center-street-addresses-for-private-delivery-service-p...
If you are also sending a state tax return by USPS or UPS, the addresses are different for each state. Check your state's tax web site for the address. If you have trouble finding it, tell us what state you are filing in and we'll try to help. Also tell us whether you are sending a payment with your state tax return.
