The limited lawful deductions
California law allows a landlord to deduct from your security deposit only for specific, limited reasons — not for whatever they wish.
The main allowable deductions are unpaid rent; the cost of cleaning the unit to make it as clean as it was when you moved in; and the cost of repairing damage you (or your guests) caused beyond normal wear and tear. In some cases, a landlord may also deduct for restoring or replacing certain personal property, like furnishings, if your agreement allows it and it is damaged beyond ordinary use.
What a landlord generally cannot deduct for is normal wear and tear — the ordinary aging and use that happens in any home — or for pre-existing problems you did not cause, or to upgrade the unit for the next tenant.
For deductions above a certain amount, the landlord usually must provide receipts or documentation. If your landlord deducted for things that seem like normal wear and tear or for repairs you did not cause, a free, confidential review can help you understand whether the deductions were lawful.
This is general information about California tenant rights, not legal advice. Every situation is different.