The city of Portland is warning taxpayers that their property tax bills may not arrive on time.

A notice posted on the city’s website said the city is currently in the process of switching to a new software system, which caused a delay in Portland’s ability to send property tax bills on time.

“We are working on them now, and expect to have them in the mail sometime during the week of Aug. 20,” the city said.

Tax bill payments are due Sept. 14.