You could write a letter or a declaration under penalty of perjury that attests to the person's residency. You could probably have your landlord notarize and sign something that affirms you were living in the apartment for 12 full months.Use the check stub from your most recent paycheck to prove your address. If you've recently moved, go ahead and change your address with your employer first. Property tax bill or statement. Records from a financial institution. Two Proofs of California Residency. To prove that you live in California, you must present two documents that contain your California physical address. A proof of residency letter is an acknowledgment or sworn statement stating that an individual resides at a specific address. If you need a proof of residency letter, you can print this free proof of residency letter template and fill in the necessary information.