Your completed and signed form must be filed with the employing withholding agent. Note: Instead of completing this form, you may file a certificate of in-state.Use our Affidavit of Domicile form to verify the last home address of a deceased person to speed up the inheritance process. Forms on this website are PDFs with fillable fields. Forms should be downloaded to your computer before filling in the fields. Use our Affidavit of Residency form to verify your home address for official purposes. For an independent student to be considered a resident of Illinois they must have physically resided in Illinois for 12 continuous full months.