Legal Question in Landlord & Tenant Law in California

Well that depends on how much security deposit you gave compared to your rent, how much notice you did give, and whether you are moving because your lease is up or you are leaving a month to month rental. If you are just moving out at the end of a lease, no notice at all is required unless the lease says so. If you are on a month to month rental, either directly or because a lease ran out and rolled over to month to month, then you can only terminate the lease on 30 days notice, as your landlord claims.

So if you are month to month, and gave less than 30 days notice, then your landlord is entitled to rent through 30 days from when you did notify them. If you notified them mid-month, then technically you are obligated to pay partial rent on the first of the next month pro rata for the number of days into the next month it takes to get to 30 days from when you gave notice. If you fail to pay that pro rata rent, then they are entitled to deduct it from your deposit. If the amount owed is less than the deposit, they must refund the balance (unless there is damage or other reasons to withhold more). If the amount owed is more than the deposit, then they can keep the whole thing and even come after you for the balance.