I am not very familiar with the specific LA County Landlord-tenant laws but I will do my best to provide some general guidance:
1. Notice for a New Lease:
Since the tenant in the first unit is on a month-to-month tenancy, you typically need to provide a 30-day written notice to make changes to the lease or terminate the tenancy. This should give the tenant sufficient time to consider the new lease terms or make other arrangements if they choose not to sign a new lease.
2. Collecting Additional Security Deposit:
If you want to collect an additional security deposit from the first unit tenant, you should again provide a 30-day written notice. The notice should include the details of the increased security deposit amount and the effective date when it will be applicable.
3. Rent Increase:
To raise the rent for the first unit tenant, you need to again provide a 30-day written notice for month-to-month tenancies. However, if the increase is more than 10% of the current rent, the notice period must be 60 days in LA County.
4. Maximum Rent Increase:
Rent control laws may apply in certain parts of LA County, and they can restrict how much and how often you can increase the rent. If the property falls under rent control regulations, you must comply with those rules. Some areas may have rent stabilization ordinances, while others do not have any specific rent control laws.
Given that this is a sensitive situation with a recent vacancy and upset tenant, it's important to approach the matter with transparency and clear communication. I'd also recommend checking with local city and county officials or even hiring a legal professional to go over the lease changes.