Legal Question in Landlord & Tenant Law in California

Technically, No. Unfortunately for landlords, tenants do this all the time.

The place to start is your lease. It may say. I draft my leases so that the landlord takes two months deposit, but agrees that if the tenant requests an inspection before the last month's rent is due, and the premises look in good enough condition that it will not take more than one month's rent for cleaning, repairs, etc., then the tenant will be permitted to use 1/2 the deposit toward last months rent. Other landlords take 1 month deposit and last month's rent. If your lease is silent on the topic, however, then you will be subject to a 3-day notice and eviction if you do not pay the last month's rent when due, unless the landlord consents to applying the deposit to the rent.