Legal Question in Landlord & Tenant Law in California

You are wrong as to the rental laws, as your landlord may also be. The payment of a security deposit is to cover any damages caused by you once you actually move out of the premises. It is not an advance payment of the last months rent, although when you leave it can be used at the landlord's option to cover any rent still owed.So you owe rent until you leave and have returned the keys and moved all of your goods out of the premises.

If you are on a lease, whether it be a one year agreement or no time is specified so it is a month to month lease, if you have breached the lease terms the landlord must serve you with a three day notice stating what the basis of the termination is for and then you have three full days to correct that breach. If it is for failure to pay the rent and you "tender" [give] the money to the landlord, then upon acceptance of any portion the landlord would have to give you a new three day notice because the amount of the rent now owing is less than what is stated in the notice. If the landlord wants you out and still wants you out even if you cure the breach, then you must be notice of the date you are to leave at least thirty full days before that date, or if you have lived there for more than one year, 60 days notice.

Within 21 days after you leave the premises, the landlord must send you a letter stating the basis of his withholding any part of your security deposit and the amount thereof, and send you a check for the balance of the security deposit if anything is left. He cna not charge you for normal wear and tear. Since you have live there five years, unless he has done so suring your living there, his having to repaint the walls and clean the carpets would not be at your expensive unless you had made excessive useage.

The issue as to late fees is unclear. There is a case or two suggesting that the late fee might have to be reasonably related to the damages the landlord actually suffers because the payment is late [lost interest, cost of preparing three day notice, calls made to you, etc.]. A flat fee of $50 plus $5 for every day the payment is late does not seem reasonably related to the landlord's damages, so you might be able to argue he is not entitled to any of that. When a landlord sets the date of the vacating of the unit, the tenant is not liable for any rent owed after that date or the date the tenant lives the unit, which ever is later.

You have not told us the date of the letter, whether the landlord accepted the January rent before or after the letter, etc., so I can not give you any additional responses.