Written by this site from official U.S. sources

Before you move out, look up your state's security deposit law: the cap, the return deadline and the penalty

High value
Evidence B
Saves money
Free
Takes minutes
No willpower

In plain words

There's no national rule for security deposits. Each state sets how much a landlord can charge, how fast it must be returned and what happens if it isn't. Read your lease, then find your state's tenant-rights agency through USA.gov. One example: in California, most landlords can charge at most one month's rent as a deposit, and must return what's left with an itemized list of deductions within 21 days after you move out.

Cost: Free. Ten minutes to look up your state's rules, plus taking photos of the unit when you move in and out.
What you get: USA.gov: before getting outside help, "read your lease carefully" and "Find help from your state agency that addresses tenant rights". Depending on your state, that may be the attorney general, a housing agency or a state tenant-rights handbook. If HUD insures or manages your building, you can report the landlord's negligence or fraud to HUD's Multifamily Housing Complaint Line. Example, California only (Civil Code § 1950.5): a landlord "shall not demand or receive security ... in excess of an amount equal to one month's rent" on top of the first month's rent. A landlord who is a natural person or an LLC whose members are all natural persons, and who owns no more than two rental properties with no more than four units in total, may charge up to two months' rent, but not to a service member. "No later than 21 calendar days after the tenant has vacated the premises," the landlord must give an itemized statement of deductions and return the rest. A bad-faith keeping of the deposit may lead to "statutory damages of up to twice the amount of the security, in addition to actual damages."
Notes: The California figures are only an example. Other states have different caps (or none), different deadlines and different penalties. Look up your own state's law. Take dated photos at move-in and move-out, and give the landlord your new address in writing. If you can't settle it, see the legal aid entry; USA.gov suggests you may need help from a lawyer.
Evidence grade: B: Supported by research but without a precise number, or based on small or single studies.
Sources: USA.gov. How to file a complaint against a landlord. https://www.usa.gov/tenant-rights
California Legislature (example of one state's law). Civil Code § 1950.5. https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=CIV&sectionNum=1950.5 （核对的是 web.archive.org 2026年9月25日的存档）

Sources checked 2026-10-12

Replaces in the original

Put the deposit amount, the refund date and the grounds for deductions in the rental contract

Content may be out of date and rules differ by place. When you actually deal with an agency, a doctor or a court, follow what local officials, doctors and lawyers tell you.