For a landlord, taking you on as a tenant is a gamble. If you can't afford the rent or disappear when it comes due, your landlord loses out. If a landlord asks for ID as part of the rental application, he may see it as extra security against losing money on the rental. You don't have to provide that ID ... but he doesn't have to rent you the apartment either.
The Background Check
It's common for a landlord to ask for your Social Security and driver's license numbers as part of a background check. Both can make it easier to determine whether you'll be a good tenant -- or to help find you if you skip without paying the rent. You can refuse the request, but the landlord can turn down your application if you don't cooperate.
Double Standard
It's illegal to discriminate against tenants based on demographics -- for example, because of race, color, religion or nationality. That doesn't just mean refusing to rent to someone of the "wrong" race, it also includes the landlord applying a different standard when screening tenants. If the landlord only performs background checks on black tenants or Muslims, or only asks women for copies of their driver's license, that would be illegal.
Sudden Surprise
It's unusual for a landlord or property manager to ask for copies after you've moved in and signed the lease, but it can happen. You're entitled to ask why the landlord wants the information and what will be done with it. If you don't get a good answer, you can refuse. Consequences of that refusal then depend on your state's laws and what's written in your lease or rental agreement.
Take Precautions
Some landlords or their staff may use personal information on your application for identity theft. Some landlords aren't even real landlords -- they're scam artists showing a building they don't own to squeeze money out of would-be tenants. Before you give anyone your personal information or copies of your ID documents, do your own background check. Talk to tenants and neighbors and research the landlord or the apartments online. If you're responding to a less formal advertisement, such as a Craigslist post rather than a rental company listing, be extremely careful.
References
Writer Bio
Fraser Sherman has written about bankruptcy law, real estate law, tax law, business law and several other categories. He lives in Durham NC with his awesome wife and two wonderful dogs. His website is frasersherman.com