Learn how to notarize a document in five simple steps. The National Notary Association has helped Notaries perform their duties for over sixty-five years.A fillable income affidavit is available on our website to type in required information and print it out to be signed and notarized. Administering an oath or affirmation is an important role of a Notary. Understand when and how to perform both types of declarations using the NNA's guide. I have obtained CLASS 9 CERTIFICATION OF TENANT HOUSEHOLD INCOME. Please be aware that forms will be displayed in a NEW browser window. An apostille certifies the validity of an Illinois notary public, county clerk, circuit clerk or local registrar. Cook County Assessor's Rules for Filing Appeals.