There are pretty specific rules they have to follow. They have 30 days to give you your deposit back or send a letter that details why they're keeping your deposit.

The amount of rent due and the cost of repairs for any damages caused by the tenant can be retained. However, if any portion of the security deposit is retained, the landlord must provide written notice to the tenant, itemizing the reasons for the withholding of any part of the security deposit. Landlords are not permitted to retain any part of the security deposit for normal wear and tear.

If a landlord fails to return the security deposit to the tenant without legal reason to do so, the tenant can commence legal action against the landlord. If the court rules against the landlord, the landlord is liable for double the amount of the withheld security deposit, plus court costs and reasonable attorney fees of the tenant.