A Principal Residence Exemption is an exemption from school operating taxes, being up 18 mills. To qualify, you must be a Michigan resident that owns and occupies the property as their principal residence and must file a timely affidavit with the City Assessor. you may also file an affidavit for any vacant properties contiguous to your principal residence, providing a separate affidavit is filed for each parcel. The deadline for filing is June 1 or November 1, depending on when the 18 mills are levied. The exemption percentage is displayed on your summer and winter tax billing statements, as well as your assessment change notice.