Security deposits
Can my landlord use my security deposit for unpaid rent?
Yes. Unpaid rent is one of the standard permitted deductions in nearly every state, but you can't be required to treat the deposit as your last month's rent while you live there.
Deposit law typically lets the landlord apply the deposit to unpaid rent, damage beyond normal wear and tear, and in some states other unpaid charges. Anything left must be returned within your state's deadline, usually with an itemized list.
Withholding your last month's rent and telling the landlord to use the deposit is risky: they may treat it as nonpayment and file for eviction, and the deposit may be needed for damage.
If deductions look wrong, ask for receipts and compare them with your move-in condition photos.
Do something about it
The Deposit recovery tool turns this answer into action.
General educational information, not legal advice. Laws vary by state and city and change over time - for a specific situation, contact a local tenant-rights organization.